1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
5 use crate::infer::canonical::Canonical;
6 use crate::ty::fold::ValidateBoundVars;
7 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
8 use crate::ty::InferTy::*;
10 self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeFoldable, TypeVisitor,
12 use crate::ty::{List, ParamEnv};
13 use polonius_engine::Atom;
14 use rustc_data_structures::captures::Captures;
15 use rustc_data_structures::intern::Interned;
17 use rustc_hir::def_id::DefId;
18 use rustc_index::vec::Idx;
19 use rustc_macros::HashStable;
20 use rustc_span::symbol::{kw, Symbol};
21 use rustc_target::abi::VariantIdx;
22 use rustc_target::spec::abi;
24 use std::cmp::Ordering;
26 use std::marker::PhantomData;
27 use std::ops::{ControlFlow, Deref, Range};
28 use ty::util::IntTypeExt;
30 use rustc_type_ir::TyKind as IrTyKind;
31 pub type TyKind<'tcx> = IrTyKind<ty::TyInterner<'tcx>>;
32 use rustc_type_ir::sty::TyKind::*;
34 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
35 #[derive(HashStable, TypeFoldable, Lift)]
36 pub struct TypeAndMut<'tcx> {
38 pub mutbl: hir::Mutability,
41 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
43 /// A "free" region `fr` can be interpreted as "some region
44 /// at least as big as the scope `fr.scope`".
45 pub struct FreeRegion {
47 pub bound_region: BoundRegionKind,
50 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
52 pub enum BoundRegionKind {
53 /// An anonymous region parameter for a given fn (&T)
56 /// Named region parameters for functions (a in &'a T)
58 /// The `DefId` is needed to distinguish free regions in
59 /// the event of shadowing.
60 BrNamed(DefId, Symbol),
62 /// Anonymous region for the implicit env pointer parameter
67 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
69 pub struct BoundRegion {
71 pub kind: BoundRegionKind,
74 impl BoundRegionKind {
75 pub fn is_named(&self) -> bool {
77 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
84 /// Defines the kinds of types used by the type system.
86 /// Types written by the user start out as [hir::TyKind](rustc_hir::TyKind) and get
87 /// converted to this representation using `AstConv::ast_ty_to_ty`.
88 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)]
90 #[rustc_diagnostic_item = "TyKind"]
91 pub enum TyKind<'tcx> {
92 /// The primitive boolean type. Written as `bool`.
95 /// The primitive character type; holds a Unicode scalar value
96 /// (a non-surrogate code point). Written as `char`.
99 /// A primitive signed integer type. For example, `i32`.
102 /// A primitive unsigned integer type. For example, `u32`.
105 /// A primitive floating-point type. For example, `f64`.
108 /// Algebraic data types (ADT). For example: structures, enumerations and unions.
110 /// For example, the type `List<i32>` would be represented using the `AdtDef`
111 /// for `struct List<T>` and the substs `[i32]`.
113 /// Note that generic parameters in fields only get lazily substituted
114 /// by using something like `adt_def.all_fields().map(|field| field.ty(tcx, substs))`.
115 Adt(AdtDef<'tcx>, SubstsRef<'tcx>),
117 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
120 /// The pointee of a string slice. Written as `str`.
123 /// An array with the given length. Written as `[T; N]`.
124 Array(Ty<'tcx>, ty::Const<'tcx>),
126 /// The pointee of an array slice. Written as `[T]`.
129 /// A raw pointer. Written as `*mut T` or `*const T`
130 RawPtr(TypeAndMut<'tcx>),
132 /// A reference; a pointer with an associated lifetime. Written as
133 /// `&'a mut T` or `&'a T`.
134 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
136 /// The anonymous type of a function declaration/definition. Each
137 /// function has a unique type.
139 /// For the function `fn foo() -> i32 { 3 }` this type would be
140 /// shown to the user as `fn() -> i32 {foo}`.
142 /// For example the type of `bar` here:
144 /// fn foo() -> i32 { 1 }
145 /// let bar = foo; // bar: fn() -> i32 {foo}
147 FnDef(DefId, SubstsRef<'tcx>),
149 /// A pointer to a function. Written as `fn() -> i32`.
151 /// Note that both functions and closures start out as either
152 /// [FnDef] or [Closure] which can be then be coerced to this variant.
154 /// For example the type of `bar` here:
157 /// fn foo() -> i32 { 1 }
158 /// let bar: fn() -> i32 = foo;
160 FnPtr(PolyFnSig<'tcx>),
162 /// A trait object. Written as `dyn for<'b> Trait<'b, Assoc = u32> + Send + 'a`.
163 Dynamic(&'tcx List<Binder<'tcx, ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
165 /// The anonymous type of a closure. Used to represent the type of `|a| a`.
167 /// Closure substs contain both the - potentially substituted - generic parameters
168 /// of its parent and some synthetic parameters. See the documentation for
169 /// [ClosureSubsts] for more details.
170 Closure(DefId, SubstsRef<'tcx>),
172 /// The anonymous type of a generator. Used to represent the type of
175 /// For more info about generator substs, visit the documentation for
176 /// [GeneratorSubsts].
177 Generator(DefId, SubstsRef<'tcx>, hir::Movability),
179 /// A type representing the types stored inside a generator.
180 /// This should only appear as part of the [GeneratorSubsts].
182 /// Note that the captured variables for generators are stored separately
183 /// using a tuple in the same way as for closures.
185 /// Unlike upvars, the witness can reference lifetimes from
186 /// inside of the generator itself. To deal with them in
187 /// the type of the generator, we convert them to higher ranked
188 /// lifetimes bound by the witness itself.
190 /// Looking at the following example, the witness for this generator
191 /// may end up as something like `for<'a> [Vec<i32>, &'a Vec<i32>]`:
193 /// ```ignore UNSOLVED (ask @compiler-errors, should this error? can we just swap the yields?)
194 /// #![feature(generators)]
196 /// let x = &vec![3];
202 GeneratorWitness(Binder<'tcx, &'tcx List<Ty<'tcx>>>),
204 /// The never type `!`.
207 /// A tuple type. For example, `(i32, bool)`.
208 Tuple(&'tcx List<Ty<'tcx>>),
210 /// The projection of an associated type. For example,
211 /// `<T as Trait<..>>::N`.
212 Projection(ProjectionTy<'tcx>),
214 /// Opaque (`impl Trait`) type found in a return type.
216 /// The `DefId` comes either from
217 /// * the `impl Trait` ast::Ty node,
218 /// * or the `type Foo = impl Trait` declaration
220 /// For RPIT the substitutions are for the generics of the function,
221 /// while for TAIT it is used for the generic parameters of the alias.
223 /// During codegen, `tcx.type_of(def_id)` can be used to get the underlying type.
224 Opaque(DefId, SubstsRef<'tcx>),
226 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}`.
229 /// Bound type variable, used to represent the `'a` in `for<'a> fn(&'a ())`.
231 /// For canonical queries, we replace inference variables with bound variables,
232 /// so e.g. when checking whether `&'_ (): Trait<_>` holds, we canonicalize that to
233 /// `for<'a, T> &'a (): Trait<T>` and then convert the introduced bound variables
234 /// back to inference variables in a new inference context when inside of the query.
236 /// See the `rustc-dev-guide` for more details about
237 /// [higher-ranked trait bounds][1] and [canonical queries][2].
239 /// [1]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
240 /// [2]: https://rustc-dev-guide.rust-lang.org/traits/canonical-queries.html
241 Bound(ty::DebruijnIndex, BoundTy),
243 /// A placeholder type, used during higher ranked subtyping to instantiate
245 Placeholder(ty::PlaceholderType),
247 /// A type variable used during type checking.
249 /// Similar to placeholders, inference variables also live in a universe to
250 /// correctly deal with higher ranked types. Though unlike placeholders,
251 /// that universe is stored in the `InferCtxt` instead of directly
252 /// inside of the type.
255 /// A placeholder for a type which could not be computed; this is
256 /// propagated to avoid useless error messages.
257 Error(DelaySpanBugEmitted),
262 impl<'tcx> TyKind<'tcx> {
264 pub fn is_primitive(&self) -> bool {
265 matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_))
268 /// Get the article ("a" or "an") to use with this type.
269 pub fn article(&self) -> &'static str {
271 Int(_) | Float(_) | Array(_, _) => "an",
272 Adt(def, _) if def.is_enum() => "an",
273 // This should never happen, but ICEing and causing the user's code
274 // to not compile felt too harsh.
283 fn article(&self) -> &'static str;
286 impl<'tcx> Article for TyKind<'tcx> {
287 /// Get the article ("a" or "an") to use with this type.
288 fn article(&self) -> &'static str {
290 Int(_) | Float(_) | Array(_, _) => "an",
291 Adt(def, _) if def.is_enum() => "an",
292 // This should never happen, but ICEing and causing the user's code
293 // to not compile felt too harsh.
300 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
301 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
302 static_assert_size!(TyKind<'_>, 32);
304 /// A closure can be modeled as a struct that looks like:
305 /// ```ignore (illustrative)
306 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
310 /// - 'l0...'li and T0...Tj are the generic parameters
311 /// in scope on the function that defined the closure,
312 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
313 /// is rather hackily encoded via a scalar type. See
314 /// `Ty::to_opt_closure_kind` for details.
315 /// - CS represents the *closure signature*, representing as a `fn()`
316 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
317 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
319 /// - U is a type parameter representing the types of its upvars, tupled up
320 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
321 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
323 /// So, for example, given this function:
324 /// ```ignore (illustrative)
325 /// fn foo<'a, T>(data: &'a mut T) {
326 /// do(|| data.count += 1)
329 /// the type of the closure would be something like:
330 /// ```ignore (illustrative)
331 /// struct Closure<'a, T, U>(...U);
333 /// Note that the type of the upvar is not specified in the struct.
334 /// You may wonder how the impl would then be able to use the upvar,
335 /// if it doesn't know it's type? The answer is that the impl is
336 /// (conceptually) not fully generic over Closure but rather tied to
337 /// instances with the expected upvar types:
338 /// ```ignore (illustrative)
339 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
343 /// You can see that the *impl* fully specified the type of the upvar
344 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
345 /// (Here, I am assuming that `data` is mut-borrowed.)
347 /// Now, the last question you may ask is: Why include the upvar types
348 /// in an extra type parameter? The reason for this design is that the
349 /// upvar types can reference lifetimes that are internal to the
350 /// creating function. In my example above, for example, the lifetime
351 /// `'b` represents the scope of the closure itself; this is some
352 /// subset of `foo`, probably just the scope of the call to the to
353 /// `do()`. If we just had the lifetime/type parameters from the
354 /// enclosing function, we couldn't name this lifetime `'b`. Note that
355 /// there can also be lifetimes in the types of the upvars themselves,
356 /// if one of them happens to be a reference to something that the
357 /// creating fn owns.
359 /// OK, you say, so why not create a more minimal set of parameters
360 /// that just includes the extra lifetime parameters? The answer is
361 /// primarily that it would be hard --- we don't know at the time when
362 /// we create the closure type what the full types of the upvars are,
363 /// nor do we know which are borrowed and which are not. In this
364 /// design, we can just supply a fresh type parameter and figure that
367 /// All right, you say, but why include the type parameters from the
368 /// original function then? The answer is that codegen may need them
369 /// when monomorphizing, and they may not appear in the upvars. A
370 /// closure could capture no variables but still make use of some
371 /// in-scope type parameter with a bound (e.g., if our example above
372 /// had an extra `U: Default`, and the closure called `U::default()`).
374 /// There is another reason. This design (implicitly) prohibits
375 /// closures from capturing themselves (except via a trait
376 /// object). This simplifies closure inference considerably, since it
377 /// means that when we infer the kind of a closure or its upvars, we
378 /// don't have to handle cycles where the decisions we make for
379 /// closure C wind up influencing the decisions we ought to make for
380 /// closure C (which would then require fixed point iteration to
381 /// handle). Plus it fixes an ICE. :P
385 /// Generators are handled similarly in `GeneratorSubsts`. The set of
386 /// type parameters is similar, but `CK` and `CS` are replaced by the
387 /// following type parameters:
389 /// * `GS`: The generator's "resume type", which is the type of the
390 /// argument passed to `resume`, and the type of `yield` expressions
391 /// inside the generator.
392 /// * `GY`: The "yield type", which is the type of values passed to
393 /// `yield` inside the generator.
394 /// * `GR`: The "return type", which is the type of value returned upon
395 /// completion of the generator.
396 /// * `GW`: The "generator witness".
397 #[derive(Copy, Clone, Debug, TypeFoldable)]
398 pub struct ClosureSubsts<'tcx> {
399 /// Lifetime and type parameters from the enclosing function,
400 /// concatenated with a tuple containing the types of the upvars.
402 /// These are separated out because codegen wants to pass them around
403 /// when monomorphizing.
404 pub substs: SubstsRef<'tcx>,
407 /// Struct returned by `split()`.
408 pub struct ClosureSubstsParts<'tcx, T> {
409 pub parent_substs: &'tcx [GenericArg<'tcx>],
410 pub closure_kind_ty: T,
411 pub closure_sig_as_fn_ptr_ty: T,
412 pub tupled_upvars_ty: T,
415 impl<'tcx> ClosureSubsts<'tcx> {
416 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
417 /// for the closure parent, alongside additional closure-specific components.
420 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
421 ) -> ClosureSubsts<'tcx> {
423 substs: tcx.mk_substs(
424 parts.parent_substs.iter().copied().chain(
425 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
427 .map(|&ty| ty.into()),
433 /// Divides the closure substs into their respective components.
434 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
435 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
436 match self.substs[..] {
438 ref parent_substs @ ..,
440 closure_sig_as_fn_ptr_ty,
442 ] => ClosureSubstsParts {
445 closure_sig_as_fn_ptr_ty,
448 _ => bug!("closure substs missing synthetics"),
452 /// Returns `true` only if enough of the synthetic types are known to
453 /// allow using all of the methods on `ClosureSubsts` without panicking.
455 /// Used primarily by `ty::print::pretty` to be able to handle closure
456 /// types that haven't had their synthetic types substituted in.
457 pub fn is_valid(self) -> bool {
458 self.substs.len() >= 3
459 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
462 /// Returns the substitutions of the closure's parent.
463 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
464 self.split().parent_substs
467 /// Returns an iterator over the list of types of captured paths by the closure.
468 /// In case there was a type error in figuring out the types of the captured path, an
469 /// empty iterator is returned.
471 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
472 match self.tupled_upvars_ty().kind() {
473 TyKind::Error(_) => None,
474 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
475 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
476 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
482 /// Returns the tuple type representing the upvars for this closure.
484 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
485 self.split().tupled_upvars_ty.expect_ty()
488 /// Returns the closure kind for this closure; may return a type
489 /// variable during inference. To get the closure kind during
490 /// inference, use `infcx.closure_kind(substs)`.
491 pub fn kind_ty(self) -> Ty<'tcx> {
492 self.split().closure_kind_ty.expect_ty()
495 /// Returns the `fn` pointer type representing the closure signature for this
497 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
498 // type is known at the time of the creation of `ClosureSubsts`,
499 // see `rustc_typeck::check::closure`.
500 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
501 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
504 /// Returns the closure kind for this closure; only usable outside
505 /// of an inference context, because in that context we know that
506 /// there are no type variables.
508 /// If you have an inference context, use `infcx.closure_kind()`.
509 pub fn kind(self) -> ty::ClosureKind {
510 self.kind_ty().to_opt_closure_kind().unwrap()
513 /// Extracts the signature from the closure.
514 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
515 let ty = self.sig_as_fn_ptr_ty();
517 ty::FnPtr(sig) => *sig,
518 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
523 /// Similar to `ClosureSubsts`; see the above documentation for more.
524 #[derive(Copy, Clone, Debug, TypeFoldable)]
525 pub struct GeneratorSubsts<'tcx> {
526 pub substs: SubstsRef<'tcx>,
529 pub struct GeneratorSubstsParts<'tcx, T> {
530 pub parent_substs: &'tcx [GenericArg<'tcx>],
535 pub tupled_upvars_ty: T,
538 impl<'tcx> GeneratorSubsts<'tcx> {
539 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
540 /// for the generator parent, alongside additional generator-specific components.
543 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
544 ) -> GeneratorSubsts<'tcx> {
546 substs: tcx.mk_substs(
547 parts.parent_substs.iter().copied().chain(
553 parts.tupled_upvars_ty,
556 .map(|&ty| ty.into()),
562 /// Divides the generator substs into their respective components.
563 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
564 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
565 match self.substs[..] {
566 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
567 GeneratorSubstsParts {
576 _ => bug!("generator substs missing synthetics"),
580 /// Returns `true` only if enough of the synthetic types are known to
581 /// allow using all of the methods on `GeneratorSubsts` without panicking.
583 /// Used primarily by `ty::print::pretty` to be able to handle generator
584 /// types that haven't had their synthetic types substituted in.
585 pub fn is_valid(self) -> bool {
586 self.substs.len() >= 5
587 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
590 /// Returns the substitutions of the generator's parent.
591 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
592 self.split().parent_substs
595 /// This describes the types that can be contained in a generator.
596 /// It will be a type variable initially and unified in the last stages of typeck of a body.
597 /// It contains a tuple of all the types that could end up on a generator frame.
598 /// The state transformation MIR pass may only produce layouts which mention types
599 /// in this tuple. Upvars are not counted here.
600 pub fn witness(self) -> Ty<'tcx> {
601 self.split().witness.expect_ty()
604 /// Returns an iterator over the list of types of captured paths by the generator.
605 /// In case there was a type error in figuring out the types of the captured path, an
606 /// empty iterator is returned.
608 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
609 match self.tupled_upvars_ty().kind() {
610 TyKind::Error(_) => None,
611 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
612 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
613 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
619 /// Returns the tuple type representing the upvars for this generator.
621 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
622 self.split().tupled_upvars_ty.expect_ty()
625 /// Returns the type representing the resume type of the generator.
626 pub fn resume_ty(self) -> Ty<'tcx> {
627 self.split().resume_ty.expect_ty()
630 /// Returns the type representing the yield type of the generator.
631 pub fn yield_ty(self) -> Ty<'tcx> {
632 self.split().yield_ty.expect_ty()
635 /// Returns the type representing the return type of the generator.
636 pub fn return_ty(self) -> Ty<'tcx> {
637 self.split().return_ty.expect_ty()
640 /// Returns the "generator signature", which consists of its yield
641 /// and return types.
643 /// N.B., some bits of the code prefers to see this wrapped in a
644 /// binder, but it never contains bound regions. Probably this
645 /// function should be removed.
646 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
647 ty::Binder::dummy(self.sig())
650 /// Returns the "generator signature", which consists of its resume, yield
651 /// and return types.
652 pub fn sig(self) -> GenSig<'tcx> {
654 resume_ty: self.resume_ty(),
655 yield_ty: self.yield_ty(),
656 return_ty: self.return_ty(),
661 impl<'tcx> GeneratorSubsts<'tcx> {
662 /// Generator has not been resumed yet.
663 pub const UNRESUMED: usize = 0;
664 /// Generator has returned or is completed.
665 pub const RETURNED: usize = 1;
666 /// Generator has been poisoned.
667 pub const POISONED: usize = 2;
669 const UNRESUMED_NAME: &'static str = "Unresumed";
670 const RETURNED_NAME: &'static str = "Returned";
671 const POISONED_NAME: &'static str = "Panicked";
673 /// The valid variant indices of this generator.
675 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
676 // FIXME requires optimized MIR
677 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
678 VariantIdx::new(0)..VariantIdx::new(num_variants)
681 /// The discriminant for the given variant. Panics if the `variant_index` is
684 pub fn discriminant_for_variant(
688 variant_index: VariantIdx,
690 // Generators don't support explicit discriminant values, so they are
691 // the same as the variant index.
692 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
693 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
696 /// The set of all discriminants for the generator, enumerated with their
699 pub fn discriminants(
703 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
704 self.variant_range(def_id, tcx).map(move |index| {
705 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
709 /// Calls `f` with a reference to the name of the enumerator for the given
711 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
713 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
714 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
715 Self::POISONED => Cow::from(Self::POISONED_NAME),
716 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
720 /// The type of the state discriminant used in the generator type.
722 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
726 /// This returns the types of the MIR locals which had to be stored across suspension points.
727 /// It is calculated in rustc_mir_transform::generator::StateTransform.
728 /// All the types here must be in the tuple in GeneratorInterior.
730 /// The locals are grouped by their variant number. Note that some locals may
731 /// be repeated in multiple variants.
737 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
738 let layout = tcx.generator_layout(def_id).unwrap();
739 layout.variant_fields.iter().map(move |variant| {
742 .map(move |field| EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
746 /// This is the types of the fields of a generator which are not stored in a
749 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
754 #[derive(Debug, Copy, Clone, HashStable)]
755 pub enum UpvarSubsts<'tcx> {
756 Closure(SubstsRef<'tcx>),
757 Generator(SubstsRef<'tcx>),
760 impl<'tcx> UpvarSubsts<'tcx> {
761 /// Returns an iterator over the list of types of captured paths by the closure/generator.
762 /// In case there was a type error in figuring out the types of the captured path, an
763 /// empty iterator is returned.
765 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
766 let tupled_tys = match self {
767 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
768 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
771 match tupled_tys.kind() {
772 TyKind::Error(_) => None,
773 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
774 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
775 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
782 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
784 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
785 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
790 /// An inline const is modeled like
791 /// ```ignore (illustrative)
792 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
796 /// - 'l0...'li and T0...Tj are the generic parameters
797 /// inherited from the item that defined the inline const,
798 /// - R represents the type of the constant.
800 /// When the inline const is instantiated, `R` is substituted as the actual inferred
801 /// type of the constant. The reason that `R` is represented as an extra type parameter
802 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
803 /// inline const can reference lifetimes that are internal to the creating function.
804 #[derive(Copy, Clone, Debug, TypeFoldable)]
805 pub struct InlineConstSubsts<'tcx> {
806 /// Generic parameters from the enclosing item,
807 /// concatenated with the inferred type of the constant.
808 pub substs: SubstsRef<'tcx>,
811 /// Struct returned by `split()`.
812 pub struct InlineConstSubstsParts<'tcx, T> {
813 pub parent_substs: &'tcx [GenericArg<'tcx>],
817 impl<'tcx> InlineConstSubsts<'tcx> {
818 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
821 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
822 ) -> InlineConstSubsts<'tcx> {
824 substs: tcx.mk_substs(
825 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
830 /// Divides the inline const substs into their respective components.
831 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
832 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
833 match self.substs[..] {
834 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
835 _ => bug!("inline const substs missing synthetics"),
839 /// Returns the substitutions of the inline const's parent.
840 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
841 self.split().parent_substs
844 /// Returns the type of this inline const.
845 pub fn ty(self) -> Ty<'tcx> {
846 self.split().ty.expect_ty()
850 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
851 #[derive(HashStable, TypeFoldable)]
852 pub enum ExistentialPredicate<'tcx> {
853 /// E.g., `Iterator`.
854 Trait(ExistentialTraitRef<'tcx>),
855 /// E.g., `Iterator::Item = T`.
856 Projection(ExistentialProjection<'tcx>),
861 impl<'tcx> ExistentialPredicate<'tcx> {
862 /// Compares via an ordering that will not change if modules are reordered or other changes are
863 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
864 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
865 use self::ExistentialPredicate::*;
866 match (*self, *other) {
867 (Trait(_), Trait(_)) => Ordering::Equal,
868 (Projection(ref a), Projection(ref b)) => {
869 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
871 (AutoTrait(ref a), AutoTrait(ref b)) => {
872 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
874 (Trait(_), _) => Ordering::Less,
875 (Projection(_), Trait(_)) => Ordering::Greater,
876 (Projection(_), _) => Ordering::Less,
877 (AutoTrait(_), _) => Ordering::Greater,
882 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
883 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
884 use crate::ty::ToPredicate;
885 match self.skip_binder() {
886 ExistentialPredicate::Trait(tr) => {
887 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
889 ExistentialPredicate::Projection(p) => {
890 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
892 ExistentialPredicate::AutoTrait(did) => {
893 let trait_ref = self.rebind(ty::TraitRef {
895 substs: tcx.mk_substs_trait(self_ty, &[]),
897 trait_ref.without_const().to_predicate(tcx)
903 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
904 /// Returns the "principal `DefId`" of this set of existential predicates.
906 /// A Rust trait object type consists (in addition to a lifetime bound)
907 /// of a set of trait bounds, which are separated into any number
908 /// of auto-trait bounds, and at most one non-auto-trait bound. The
909 /// non-auto-trait bound is called the "principal" of the trait
912 /// Only the principal can have methods or type parameters (because
913 /// auto traits can have neither of them). This is important, because
914 /// it means the auto traits can be treated as an unordered set (methods
915 /// would force an order for the vtable, while relating traits with
916 /// type parameters without knowing the order to relate them in is
917 /// a rather non-trivial task).
919 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
920 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
921 /// are the set `{Sync}`.
923 /// It is also possible to have a "trivial" trait object that
924 /// consists only of auto traits, with no principal - for example,
925 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
926 /// is `{Send, Sync}`, while there is no principal. These trait objects
927 /// have a "trivial" vtable consisting of just the size, alignment,
929 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
931 .map_bound(|this| match this {
932 ExistentialPredicate::Trait(tr) => Some(tr),
938 pub fn principal_def_id(&self) -> Option<DefId> {
939 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
943 pub fn projection_bounds<'a>(
945 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
946 self.iter().filter_map(|predicate| {
948 .map_bound(|pred| match pred {
949 ExistentialPredicate::Projection(projection) => Some(projection),
957 pub fn auto_traits<'a>(
959 ) -> impl Iterator<Item = DefId> + rustc_data_structures::captures::Captures<'tcx> + 'a {
960 self.iter().filter_map(|predicate| match predicate.skip_binder() {
961 ExistentialPredicate::AutoTrait(did) => Some(did),
967 /// A complete reference to a trait. These take numerous guises in syntax,
968 /// but perhaps the most recognizable form is in a where-clause:
969 /// ```ignore (illustrative)
972 /// This would be represented by a trait-reference where the `DefId` is the
973 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
974 /// and `U` as parameter 1.
976 /// Trait references also appear in object types like `Foo<U>`, but in
977 /// that case the `Self` parameter is absent from the substitutions.
978 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
979 #[derive(HashStable, TypeFoldable)]
980 pub struct TraitRef<'tcx> {
982 pub substs: SubstsRef<'tcx>,
985 impl<'tcx> TraitRef<'tcx> {
986 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
987 TraitRef { def_id, substs }
990 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
991 /// are the parameters defined on trait.
992 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
993 ty::Binder::dummy(TraitRef {
995 substs: InternalSubsts::identity_for_item(tcx, def_id),
1000 pub fn self_ty(&self) -> Ty<'tcx> {
1001 self.substs.type_at(0)
1007 substs: SubstsRef<'tcx>,
1008 ) -> ty::TraitRef<'tcx> {
1009 let defs = tcx.generics_of(trait_id);
1010 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
1014 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
1016 impl<'tcx> PolyTraitRef<'tcx> {
1017 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
1018 self.map_bound_ref(|tr| tr.self_ty())
1021 pub fn def_id(&self) -> DefId {
1022 self.skip_binder().def_id
1025 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
1026 self.map_bound(|trait_ref| ty::TraitPredicate {
1028 constness: ty::BoundConstness::NotConst,
1029 polarity: ty::ImplPolarity::Positive,
1033 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
1034 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
1035 self.map_bound(|trait_ref| ty::TraitPredicate {
1037 constness: ty::BoundConstness::NotConst,
1038 polarity: ty::ImplPolarity::Negative,
1043 /// An existential reference to a trait, where `Self` is erased.
1044 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
1045 /// ```ignore (illustrative)
1046 /// exists T. T: Trait<'a, 'b, X, Y>
1048 /// The substitutions don't include the erased `Self`, only trait
1049 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
1050 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1051 #[derive(HashStable, TypeFoldable)]
1052 pub struct ExistentialTraitRef<'tcx> {
1054 pub substs: SubstsRef<'tcx>,
1057 impl<'tcx> ExistentialTraitRef<'tcx> {
1058 pub fn erase_self_ty(
1060 trait_ref: ty::TraitRef<'tcx>,
1061 ) -> ty::ExistentialTraitRef<'tcx> {
1062 // Assert there is a Self.
1063 trait_ref.substs.type_at(0);
1065 ty::ExistentialTraitRef {
1066 def_id: trait_ref.def_id,
1067 substs: tcx.intern_substs(&trait_ref.substs[1..]),
1071 /// Object types don't have a self type specified. Therefore, when
1072 /// we convert the principal trait-ref into a normal trait-ref,
1073 /// you must give *some* self type. A common choice is `mk_err()`
1074 /// or some placeholder type.
1075 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
1076 // otherwise the escaping vars would be captured by the binder
1077 // debug_assert!(!self_ty.has_escaping_bound_vars());
1079 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
1083 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
1085 impl<'tcx> PolyExistentialTraitRef<'tcx> {
1086 pub fn def_id(&self) -> DefId {
1087 self.skip_binder().def_id
1090 /// Object types don't have a self type specified. Therefore, when
1091 /// we convert the principal trait-ref into a normal trait-ref,
1092 /// you must give *some* self type. A common choice is `mk_err()`
1093 /// or some placeholder type.
1094 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
1095 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
1099 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1100 #[derive(Encodable, Decodable, HashStable)]
1101 pub struct EarlyBinder<T>(pub T);
1103 impl<T> EarlyBinder<T> {
1104 pub fn as_ref(&self) -> EarlyBinder<&T> {
1105 EarlyBinder(&self.0)
1108 pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<U>
1112 self.as_ref().map_bound(f)
1115 pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<U>
1119 let value = f(self.0);
1123 pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<U>, E>
1125 F: FnOnce(T) -> Result<U, E>,
1127 let value = f(self.0)?;
1128 Ok(EarlyBinder(value))
1132 impl<T> EarlyBinder<Option<T>> {
1133 pub fn transpose(self) -> Option<EarlyBinder<T>> {
1134 self.0.map(|v| EarlyBinder(v))
1138 impl<T, U> EarlyBinder<(T, U)> {
1139 pub fn transpose_tuple2(self) -> (EarlyBinder<T>, EarlyBinder<U>) {
1140 (EarlyBinder(self.0.0), EarlyBinder(self.0.1))
1144 pub struct EarlyBinderIter<T> {
1148 impl<T: IntoIterator> EarlyBinder<T> {
1149 pub fn transpose_iter(self) -> EarlyBinderIter<T::IntoIter> {
1150 EarlyBinderIter { t: self.0.into_iter() }
1154 impl<T: Iterator> Iterator for EarlyBinderIter<T> {
1155 type Item = EarlyBinder<T::Item>;
1157 fn next(&mut self) -> Option<Self::Item> {
1158 self.t.next().map(|i| EarlyBinder(i))
1162 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1163 #[derive(HashStable)]
1164 pub enum BoundVariableKind {
1166 Region(BoundRegionKind),
1170 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
1171 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
1172 /// (which would be represented by the type `PolyTraitRef ==
1173 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
1174 /// erase, or otherwise "discharge" these bound vars, we change the
1175 /// type from `Binder<'tcx, T>` to just `T` (see
1176 /// e.g., `liberate_late_bound_regions`).
1178 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
1179 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1180 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
1182 impl<'tcx, T> Binder<'tcx, T>
1184 T: TypeFoldable<'tcx>,
1186 /// Wraps `value` in a binder, asserting that `value` does not
1187 /// contain any bound vars that would be bound by the
1188 /// binder. This is commonly used to 'inject' a value T into a
1189 /// different binding level.
1190 pub fn dummy(value: T) -> Binder<'tcx, T> {
1191 assert!(!value.has_escaping_bound_vars());
1192 Binder(value, ty::List::empty())
1195 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
1196 if cfg!(debug_assertions) {
1197 let mut validator = ValidateBoundVars::new(vars);
1198 value.visit_with(&mut validator);
1204 impl<'tcx, T> Binder<'tcx, T> {
1205 /// Skips the binder and returns the "bound" value. This is a
1206 /// risky thing to do because it's easy to get confused about
1207 /// De Bruijn indices and the like. It is usually better to
1208 /// discharge the binder using `no_bound_vars` or
1209 /// `replace_late_bound_regions` or something like
1210 /// that. `skip_binder` is only valid when you are either
1211 /// extracting data that has nothing to do with bound vars, you
1212 /// are doing some sort of test that does not involve bound
1213 /// regions, or you are being very careful about your depth
1216 /// Some examples where `skip_binder` is reasonable:
1218 /// - extracting the `DefId` from a PolyTraitRef;
1219 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1220 /// a type parameter `X`, since the type `X` does not reference any regions
1221 pub fn skip_binder(self) -> T {
1225 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1229 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1230 Binder(&self.0, self.1)
1233 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1237 let value = f(&self.0);
1238 Binder(value, self.1)
1241 pub fn map_bound_ref<F, U: TypeFoldable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1245 self.as_ref().map_bound(f)
1248 pub fn map_bound<F, U: TypeFoldable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1252 let value = f(self.0);
1253 if cfg!(debug_assertions) {
1254 let mut validator = ValidateBoundVars::new(self.1);
1255 value.visit_with(&mut validator);
1257 Binder(value, self.1)
1260 pub fn try_map_bound<F, U: TypeFoldable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1262 F: FnOnce(T) -> Result<U, E>,
1264 let value = f(self.0)?;
1265 if cfg!(debug_assertions) {
1266 let mut validator = ValidateBoundVars::new(self.1);
1267 value.visit_with(&mut validator);
1269 Ok(Binder(value, self.1))
1272 /// Wraps a `value` in a binder, using the same bound variables as the
1273 /// current `Binder`. This should not be used if the new value *changes*
1274 /// the bound variables. Note: the (old or new) value itself does not
1275 /// necessarily need to *name* all the bound variables.
1277 /// This currently doesn't do anything different than `bind`, because we
1278 /// don't actually track bound vars. However, semantically, it is different
1279 /// because bound vars aren't allowed to change here, whereas they are
1280 /// in `bind`. This may be (debug) asserted in the future.
1281 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1283 U: TypeFoldable<'tcx>,
1285 if cfg!(debug_assertions) {
1286 let mut validator = ValidateBoundVars::new(self.bound_vars());
1287 value.visit_with(&mut validator);
1289 Binder(value, self.1)
1292 /// Unwraps and returns the value within, but only if it contains
1293 /// no bound vars at all. (In other words, if this binder --
1294 /// and indeed any enclosing binder -- doesn't bind anything at
1295 /// all.) Otherwise, returns `None`.
1297 /// (One could imagine having a method that just unwraps a single
1298 /// binder, but permits late-bound vars bound by enclosing
1299 /// binders, but that would require adjusting the debruijn
1300 /// indices, and given the shallow binding structure we often use,
1301 /// would not be that useful.)
1302 pub fn no_bound_vars(self) -> Option<T>
1304 T: TypeFoldable<'tcx>,
1306 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1309 /// Splits the contents into two things that share the same binder
1310 /// level as the original, returning two distinct binders.
1312 /// `f` should consider bound regions at depth 1 to be free, and
1313 /// anything it produces with bound regions at depth 1 will be
1314 /// bound in the resulting return values.
1315 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1317 F: FnOnce(T) -> (U, V),
1319 let (u, v) = f(self.0);
1320 (Binder(u, self.1), Binder(v, self.1))
1324 impl<'tcx, T> Binder<'tcx, Option<T>> {
1325 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1326 let bound_vars = self.1;
1327 self.0.map(|v| Binder(v, bound_vars))
1331 /// Represents the projection of an associated type. In explicit UFCS
1332 /// form this would be written `<T as Trait<..>>::N`.
1333 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1334 #[derive(HashStable, TypeFoldable)]
1335 pub struct ProjectionTy<'tcx> {
1336 /// The parameters of the associated item.
1337 pub substs: SubstsRef<'tcx>,
1339 /// The `DefId` of the `TraitItem` for the associated type `N`.
1341 /// Note that this is not the `DefId` of the `TraitRef` containing this
1342 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
1343 pub item_def_id: DefId,
1346 impl<'tcx> ProjectionTy<'tcx> {
1347 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1348 tcx.associated_item(self.item_def_id).container.id()
1351 /// Extracts the underlying trait reference and own substs from this projection.
1352 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1353 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1354 pub fn trait_ref_and_own_substs(
1357 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1358 let def_id = tcx.associated_item(self.item_def_id).container.id();
1359 let trait_generics = tcx.generics_of(def_id);
1361 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1362 &self.substs[trait_generics.count()..],
1366 /// Extracts the underlying trait reference from this projection.
1367 /// For example, if this is a projection of `<T as Iterator>::Item`,
1368 /// then this function would return a `T: Iterator` trait reference.
1370 /// WARNING: This will drop the substs for generic associated types
1371 /// consider calling [Self::trait_ref_and_own_substs] to get those
1373 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1374 let def_id = self.trait_def_id(tcx);
1375 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1378 pub fn self_ty(&self) -> Ty<'tcx> {
1379 self.substs.type_at(0)
1383 #[derive(Copy, Clone, Debug, TypeFoldable)]
1384 pub struct GenSig<'tcx> {
1385 pub resume_ty: Ty<'tcx>,
1386 pub yield_ty: Ty<'tcx>,
1387 pub return_ty: Ty<'tcx>,
1390 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1392 /// Signature of a function type, which we have arbitrarily
1393 /// decided to use to refer to the input/output types.
1395 /// - `inputs`: is the list of arguments and their modes.
1396 /// - `output`: is the return type.
1397 /// - `c_variadic`: indicates whether this is a C-variadic function.
1398 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1399 #[derive(HashStable, TypeFoldable)]
1400 pub struct FnSig<'tcx> {
1401 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1402 pub c_variadic: bool,
1403 pub unsafety: hir::Unsafety,
1407 impl<'tcx> FnSig<'tcx> {
1408 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1409 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1412 pub fn output(&self) -> Ty<'tcx> {
1413 self.inputs_and_output[self.inputs_and_output.len() - 1]
1416 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1418 fn fake() -> FnSig<'tcx> {
1420 inputs_and_output: List::empty(),
1422 unsafety: hir::Unsafety::Normal,
1423 abi: abi::Abi::Rust,
1428 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1430 impl<'tcx> PolyFnSig<'tcx> {
1432 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1433 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1436 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1437 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1439 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1440 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1443 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1444 self.map_bound_ref(|fn_sig| fn_sig.output())
1446 pub fn c_variadic(&self) -> bool {
1447 self.skip_binder().c_variadic
1449 pub fn unsafety(&self) -> hir::Unsafety {
1450 self.skip_binder().unsafety
1452 pub fn abi(&self) -> abi::Abi {
1453 self.skip_binder().abi
1457 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1459 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1460 #[derive(HashStable)]
1461 pub struct ParamTy {
1466 impl<'tcx> ParamTy {
1467 pub fn new(index: u32, name: Symbol) -> ParamTy {
1468 ParamTy { index, name }
1471 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1472 ParamTy::new(def.index, def.name)
1476 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1477 tcx.mk_ty_param(self.index, self.name)
1481 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1482 #[derive(HashStable)]
1483 pub struct ParamConst {
1489 pub fn new(index: u32, name: Symbol) -> ParamConst {
1490 ParamConst { index, name }
1493 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1494 ParamConst::new(def.index, def.name)
1498 /// Use this rather than `RegionKind`, whenever possible.
1499 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1500 #[rustc_pass_by_value]
1501 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind>);
1503 impl<'tcx> Deref for Region<'tcx> {
1504 type Target = RegionKind;
1506 fn deref(&self) -> &RegionKind {
1511 impl<'tcx> fmt::Debug for Region<'tcx> {
1512 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1513 write!(f, "{:?}", self.kind())
1517 /// Representation of regions. Note that the NLL checker uses a distinct
1518 /// representation of regions. For this reason, it internally replaces all the
1519 /// regions with inference variables -- the index of the variable is then used
1520 /// to index into internal NLL data structures. See `rustc_const_eval::borrow_check`
1521 /// module for more information.
1523 /// Note: operations are on the wrapper `Region` type, which is interned,
1524 /// rather than this type.
1526 /// ## The Region lattice within a given function
1528 /// In general, the region lattice looks like
1531 /// static ----------+-----...------+ (greatest)
1533 /// early-bound and | |
1534 /// free regions | |
1537 /// empty(root) placeholder(U1) |
1539 /// | / placeholder(Un)
1544 /// empty(Un) -------- (smallest)
1547 /// Early-bound/free regions are the named lifetimes in scope from the
1548 /// function declaration. They have relationships to one another
1549 /// determined based on the declared relationships from the
1552 /// Note that inference variables and bound regions are not included
1553 /// in this diagram. In the case of inference variables, they should
1554 /// be inferred to some other region from the diagram. In the case of
1555 /// bound regions, they are excluded because they don't make sense to
1556 /// include -- the diagram indicates the relationship between free
1559 /// ## Inference variables
1561 /// During region inference, we sometimes create inference variables,
1562 /// represented as `ReVar`. These will be inferred by the code in
1563 /// `infer::lexical_region_resolve` to some free region from the
1564 /// lattice above (the minimal region that meets the
1567 /// During NLL checking, where regions are defined differently, we
1568 /// also use `ReVar` -- in that case, the index is used to index into
1569 /// the NLL region checker's data structures. The variable may in fact
1570 /// represent either a free region or an inference variable, in that
1573 /// ## Bound Regions
1575 /// These are regions that are stored behind a binder and must be substituted
1576 /// with some concrete region before being used. There are two kind of
1577 /// bound regions: early-bound, which are bound in an item's `Generics`,
1578 /// and are substituted by an `InternalSubsts`, and late-bound, which are part of
1579 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1580 /// the likes of `liberate_late_bound_regions`. The distinction exists
1581 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1583 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1584 /// outside their binder, e.g., in types passed to type inference, and
1585 /// should first be substituted (by placeholder regions, free regions,
1586 /// or region variables).
1588 /// ## Placeholder and Free Regions
1590 /// One often wants to work with bound regions without knowing their precise
1591 /// identity. For example, when checking a function, the lifetime of a borrow
1592 /// can end up being assigned to some region parameter. In these cases,
1593 /// it must be ensured that bounds on the region can't be accidentally
1594 /// assumed without being checked.
1596 /// To do this, we replace the bound regions with placeholder markers,
1597 /// which don't satisfy any relation not explicitly provided.
1599 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1600 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1601 /// to be used. These also support explicit bounds: both the internally-stored
1602 /// *scope*, which the region is assumed to outlive, as well as other
1603 /// relations stored in the `FreeRegionMap`. Note that these relations
1604 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1605 /// `resolve_regions_and_report_errors`.
1607 /// When working with higher-ranked types, some region relations aren't
1608 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1609 /// `RePlaceholder` is designed for this purpose. In these contexts,
1610 /// there's also the risk that some inference variable laying around will
1611 /// get unified with your placeholder region: if you want to check whether
1612 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1613 /// with a placeholder region `'%a`, the variable `'_` would just be
1614 /// instantiated to the placeholder region `'%a`, which is wrong because
1615 /// the inference variable is supposed to satisfy the relation
1616 /// *for every value of the placeholder region*. To ensure that doesn't
1617 /// happen, you can use `leak_check`. This is more clearly explained
1618 /// by the [rustc dev guide].
1620 /// [1]: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1621 /// [2]: https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1622 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
1623 #[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)]
1624 pub enum RegionKind {
1625 /// Region bound in a type or fn declaration which will be
1626 /// substituted 'early' -- that is, at the same time when type
1627 /// parameters are substituted.
1628 ReEarlyBound(EarlyBoundRegion),
1630 /// Region bound in a function scope, which will be substituted when the
1631 /// function is called.
1632 ReLateBound(ty::DebruijnIndex, BoundRegion),
1634 /// When checking a function body, the types of all arguments and so forth
1635 /// that refer to bound region parameters are modified to refer to free
1636 /// region parameters.
1639 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1642 /// A region variable. Should not exist outside of type inference.
1645 /// A placeholder region -- basically, the higher-ranked version of `ReFree`.
1646 /// Should not exist outside of type inference.
1647 RePlaceholder(ty::PlaceholderRegion),
1649 /// Empty lifetime is for data that is never accessed. We tag the
1650 /// empty lifetime with a universe -- the idea is that we don't
1651 /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable.
1652 /// Therefore, the `'empty` in a universe `U` is less than all
1653 /// regions visible from `U`, but not less than regions not visible
1655 ReEmpty(ty::UniverseIndex),
1657 /// Erased region, used by trait selection, in MIR and during codegen.
1661 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
1662 pub struct EarlyBoundRegion {
1668 /// A **`const`** **v**ariable **ID**.
1669 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1670 pub struct ConstVid<'tcx> {
1672 pub phantom: PhantomData<&'tcx ()>,
1675 rustc_index::newtype_index! {
1676 /// A **region** (lifetime) **v**ariable **ID**.
1677 pub struct RegionVid {
1678 DEBUG_FORMAT = custom,
1682 impl Atom for RegionVid {
1683 fn index(self) -> usize {
1688 rustc_index::newtype_index! {
1689 pub struct BoundVar { .. }
1692 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1693 #[derive(HashStable)]
1694 pub struct BoundTy {
1696 pub kind: BoundTyKind,
1699 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1700 #[derive(HashStable)]
1701 pub enum BoundTyKind {
1706 impl From<BoundVar> for BoundTy {
1707 fn from(var: BoundVar) -> Self {
1708 BoundTy { var, kind: BoundTyKind::Anon }
1712 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1713 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1714 #[derive(HashStable, TypeFoldable)]
1715 pub struct ExistentialProjection<'tcx> {
1716 pub item_def_id: DefId,
1717 pub substs: SubstsRef<'tcx>,
1718 pub term: Term<'tcx>,
1721 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1723 impl<'tcx> ExistentialProjection<'tcx> {
1724 /// Extracts the underlying existential trait reference from this projection.
1725 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1726 /// then this function would return an `exists T. T: Iterator` existential trait
1728 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1729 let def_id = tcx.associated_item(self.item_def_id).container.id();
1730 let subst_count = tcx.generics_of(def_id).count() - 1;
1731 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1732 ty::ExistentialTraitRef { def_id, substs }
1735 pub fn with_self_ty(
1739 ) -> ty::ProjectionPredicate<'tcx> {
1740 // otherwise the escaping regions would be captured by the binders
1741 debug_assert!(!self_ty.has_escaping_bound_vars());
1743 ty::ProjectionPredicate {
1744 projection_ty: ty::ProjectionTy {
1745 item_def_id: self.item_def_id,
1746 substs: tcx.mk_substs_trait(self_ty, self.substs),
1752 pub fn erase_self_ty(
1754 projection_predicate: ty::ProjectionPredicate<'tcx>,
1756 // Assert there is a Self.
1757 projection_predicate.projection_ty.substs.type_at(0);
1760 item_def_id: projection_predicate.projection_ty.item_def_id,
1761 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1762 term: projection_predicate.term,
1767 impl<'tcx> PolyExistentialProjection<'tcx> {
1768 pub fn with_self_ty(
1772 ) -> ty::PolyProjectionPredicate<'tcx> {
1773 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1776 pub fn item_def_id(&self) -> DefId {
1777 self.skip_binder().item_def_id
1781 /// Region utilities
1782 impl<'tcx> Region<'tcx> {
1783 pub fn kind(self) -> RegionKind {
1787 /// Is this region named by the user?
1788 pub fn has_name(self) -> bool {
1790 ty::ReEarlyBound(ebr) => ebr.has_name(),
1791 ty::ReLateBound(_, br) => br.kind.is_named(),
1792 ty::ReFree(fr) => fr.bound_region.is_named(),
1793 ty::ReStatic => true,
1794 ty::ReVar(..) => false,
1795 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1796 ty::ReEmpty(_) => false,
1797 ty::ReErased => false,
1802 pub fn is_static(self) -> bool {
1803 matches!(*self, ty::ReStatic)
1807 pub fn is_erased(self) -> bool {
1808 matches!(*self, ty::ReErased)
1812 pub fn is_late_bound(self) -> bool {
1813 matches!(*self, ty::ReLateBound(..))
1817 pub fn is_placeholder(self) -> bool {
1818 matches!(*self, ty::RePlaceholder(..))
1822 pub fn is_empty(self) -> bool {
1823 matches!(*self, ty::ReEmpty(..))
1827 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1829 ty::ReLateBound(debruijn, _) => debruijn >= index,
1834 pub fn type_flags(self) -> TypeFlags {
1835 let mut flags = TypeFlags::empty();
1839 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1840 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1841 flags = flags | TypeFlags::HAS_RE_INFER;
1843 ty::RePlaceholder(..) => {
1844 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1845 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1846 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1848 ty::ReEarlyBound(..) => {
1849 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1850 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1851 flags = flags | TypeFlags::HAS_RE_PARAM;
1853 ty::ReFree { .. } => {
1854 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1855 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1857 ty::ReEmpty(_) | ty::ReStatic => {
1858 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1860 ty::ReLateBound(..) => {
1861 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1864 flags = flags | TypeFlags::HAS_RE_ERASED;
1868 debug!("type_flags({:?}) = {:?}", self, flags);
1873 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1874 /// For example, consider the regions in this snippet of code:
1876 /// ```ignore (illustrative)
1878 /// // ^^ -- early bound, declared on an impl
1880 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1881 /// // ^^ ^^ ^ anonymous, late-bound
1882 /// // | early-bound, appears in where-clauses
1883 /// // late-bound, appears only in fn args
1888 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1889 /// of the impl, and for all the other highlighted regions, it
1890 /// would return the `DefId` of the function. In other cases (not shown), this
1891 /// function might return the `DefId` of a closure.
1892 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1894 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1895 ty::ReFree(fr) => fr.scope,
1896 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1902 impl<'tcx> Ty<'tcx> {
1904 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1909 pub fn flags(self) -> TypeFlags {
1914 pub fn is_unit(self) -> bool {
1916 Tuple(ref tys) => tys.is_empty(),
1922 pub fn is_never(self) -> bool {
1923 matches!(self.kind(), Never)
1927 pub fn is_primitive(self) -> bool {
1928 self.kind().is_primitive()
1932 pub fn is_adt(self) -> bool {
1933 matches!(self.kind(), Adt(..))
1937 pub fn is_ref(self) -> bool {
1938 matches!(self.kind(), Ref(..))
1942 pub fn is_ty_var(self) -> bool {
1943 matches!(self.kind(), Infer(TyVar(_)))
1947 pub fn ty_vid(self) -> Option<ty::TyVid> {
1949 &Infer(TyVar(vid)) => Some(vid),
1955 pub fn is_ty_infer(self) -> bool {
1956 matches!(self.kind(), Infer(_))
1960 pub fn is_phantom_data(self) -> bool {
1961 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1965 pub fn is_bool(self) -> bool {
1966 *self.kind() == Bool
1969 /// Returns `true` if this type is a `str`.
1971 pub fn is_str(self) -> bool {
1976 pub fn is_param(self, index: u32) -> bool {
1978 ty::Param(ref data) => data.index == index,
1984 pub fn is_slice(self) -> bool {
1985 matches!(self.kind(), Slice(_))
1989 pub fn is_array_slice(self) -> bool {
1992 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1998 pub fn is_array(self) -> bool {
1999 matches!(self.kind(), Array(..))
2003 pub fn is_simd(self) -> bool {
2005 Adt(def, _) => def.repr().simd(),
2010 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2012 Array(ty, _) | Slice(ty) => *ty,
2013 Str => tcx.types.u8,
2014 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
2018 pub fn expect_opaque_type(self) -> ty::OpaqueTypeKey<'tcx> {
2019 match *self.kind() {
2020 Opaque(def_id, substs) => ty::OpaqueTypeKey { def_id, substs },
2021 _ => bug!("`expect_opaque_type` called on non-opaque type: {}", self),
2025 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
2027 Adt(def, substs) => {
2028 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
2029 let variant = def.non_enum_variant();
2030 let f0_ty = variant.fields[0].ty(tcx, substs);
2032 match f0_ty.kind() {
2033 // If the first field is an array, we assume it is the only field and its
2034 // elements are the SIMD components.
2035 Array(f0_elem_ty, f0_len) => {
2036 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
2037 // The way we evaluate the `N` in `[T; N]` here only works since we use
2038 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
2039 // if we use it in generic code. See the `simd-array-trait` ui test.
2040 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
2042 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
2043 // all have the same type).
2044 _ => (variant.fields.len() as u64, f0_ty),
2047 _ => bug!("`simd_size_and_type` called on invalid type"),
2052 pub fn is_region_ptr(self) -> bool {
2053 matches!(self.kind(), Ref(..))
2057 pub fn is_mutable_ptr(self) -> bool {
2060 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
2061 | Ref(_, _, hir::Mutability::Mut)
2065 /// Get the mutability of the reference or `None` when not a reference
2067 pub fn ref_mutability(self) -> Option<hir::Mutability> {
2069 Ref(_, _, mutability) => Some(*mutability),
2075 pub fn is_unsafe_ptr(self) -> bool {
2076 matches!(self.kind(), RawPtr(_))
2079 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
2081 pub fn is_any_ptr(self) -> bool {
2082 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
2086 pub fn is_box(self) -> bool {
2088 Adt(def, _) => def.is_box(),
2093 /// Panics if called on any type other than `Box<T>`.
2094 pub fn boxed_ty(self) -> Ty<'tcx> {
2096 Adt(def, substs) if def.is_box() => substs.type_at(0),
2097 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
2101 /// A scalar type is one that denotes an atomic datum, with no sub-components.
2102 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
2103 /// contents are abstract to rustc.)
2105 pub fn is_scalar(self) -> bool {
2115 | Infer(IntVar(_) | FloatVar(_))
2119 /// Returns `true` if this type is a floating point type.
2121 pub fn is_floating_point(self) -> bool {
2122 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
2126 pub fn is_trait(self) -> bool {
2127 matches!(self.kind(), Dynamic(..))
2131 pub fn is_enum(self) -> bool {
2132 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
2136 pub fn is_union(self) -> bool {
2137 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
2141 pub fn is_closure(self) -> bool {
2142 matches!(self.kind(), Closure(..))
2146 pub fn is_generator(self) -> bool {
2147 matches!(self.kind(), Generator(..))
2151 pub fn is_integral(self) -> bool {
2152 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
2156 pub fn is_fresh_ty(self) -> bool {
2157 matches!(self.kind(), Infer(FreshTy(_)))
2161 pub fn is_fresh(self) -> bool {
2162 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
2166 pub fn is_char(self) -> bool {
2167 matches!(self.kind(), Char)
2171 pub fn is_numeric(self) -> bool {
2172 self.is_integral() || self.is_floating_point()
2176 pub fn is_signed(self) -> bool {
2177 matches!(self.kind(), Int(_))
2181 pub fn is_ptr_sized_integral(self) -> bool {
2182 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
2186 pub fn has_concrete_skeleton(self) -> bool {
2187 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
2190 /// Checks whether a type recursively contains another type
2192 /// Example: `Option<()>` contains `()`
2193 pub fn contains(self, other: Ty<'tcx>) -> bool {
2194 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
2196 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
2199 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
2200 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
2204 let cf = self.visit_with(&mut ContainsTyVisitor(other));
2208 /// Returns the type and mutability of `*ty`.
2210 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2211 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2212 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2214 Adt(def, _) if def.is_box() => {
2215 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
2217 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
2218 RawPtr(mt) if explicit => Some(*mt),
2223 /// Returns the type of `ty[i]`.
2224 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
2226 Array(ty, _) | Slice(ty) => Some(*ty),
2231 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2233 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
2236 // ignore errors (#54954)
2237 ty::Binder::dummy(FnSig::fake())
2239 Closure(..) => bug!(
2240 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
2242 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
2247 pub fn is_fn(self) -> bool {
2248 matches!(self.kind(), FnDef(..) | FnPtr(_))
2252 pub fn is_fn_ptr(self) -> bool {
2253 matches!(self.kind(), FnPtr(_))
2257 pub fn is_impl_trait(self) -> bool {
2258 matches!(self.kind(), Opaque(..))
2262 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
2264 Adt(adt, _) => Some(*adt),
2269 /// Iterates over tuple fields.
2270 /// Panics when called on anything but a tuple.
2272 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
2274 Tuple(substs) => substs,
2275 _ => bug!("tuple_fields called on non-tuple"),
2279 /// If the type contains variants, returns the valid range of variant indices.
2281 // FIXME: This requires the optimized MIR in the case of generators.
2283 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2285 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2286 TyKind::Generator(def_id, substs, _) => {
2287 Some(substs.as_generator().variant_range(*def_id, tcx))
2293 /// If the type contains variants, returns the variant for `variant_index`.
2294 /// Panics if `variant_index` is out of range.
2296 // FIXME: This requires the optimized MIR in the case of generators.
2298 pub fn discriminant_for_variant(
2301 variant_index: VariantIdx,
2302 ) -> Option<Discr<'tcx>> {
2304 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2305 // This can actually happen during CTFE, see
2306 // https://github.com/rust-lang/rust/issues/89765.
2309 TyKind::Adt(adt, _) if adt.is_enum() => {
2310 Some(adt.discriminant_for_variant(tcx, variant_index))
2312 TyKind::Generator(def_id, substs, _) => {
2313 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2319 /// Returns the type of the discriminant of this type.
2320 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2322 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2323 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2325 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2326 let assoc_items = tcx.associated_item_def_ids(
2327 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2329 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2348 | ty::GeneratorWitness(..)
2352 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2355 | ty::Placeholder(_)
2356 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2357 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2362 /// Returns the type of metadata for (potentially fat) pointers to this type,
2363 /// and a boolean signifying if this is conditional on this type being `Sized`.
2364 pub fn ptr_metadata_ty(
2367 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2368 ) -> (Ty<'tcx>, bool) {
2369 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2372 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2383 | ty::GeneratorWitness(..)
2388 // Extern types have metadata = ().
2390 // If returned by `struct_tail_without_normalization` this is a unit struct
2391 // without any fields, or not a struct, and therefore is Sized.
2393 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2394 // a.k.a. unit type, which is Sized
2395 | ty::Tuple(..) => (tcx.types.unit, false),
2397 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2398 ty::Dynamic(..) => {
2399 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2400 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2403 // type parameters only have unit metadata if they're sized, so return true
2404 // to make sure we double check this during confirmation
2405 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2407 ty::Infer(ty::TyVar(_))
2409 | ty::Placeholder(..)
2410 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2411 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2416 /// When we create a closure, we record its kind (i.e., what trait
2417 /// it implements) into its `ClosureSubsts` using a type
2418 /// parameter. This is kind of a phantom type, except that the
2419 /// most convenient thing for us to are the integral types. This
2420 /// function converts such a special type into the closure
2421 /// kind. To go the other way, use
2422 /// `tcx.closure_kind_ty(closure_kind)`.
2424 /// Note that during type checking, we use an inference variable
2425 /// to represent the closure kind, because it has not yet been
2426 /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
2427 /// is complete, that type variable will be unified.
2428 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2430 Int(int_ty) => match int_ty {
2431 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2432 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2433 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2434 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2437 // "Bound" types appear in canonical queries when the
2438 // closure type is not yet known
2439 Bound(..) | Infer(_) => None,
2441 Error(_) => Some(ty::ClosureKind::Fn),
2443 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2447 /// Fast path helper for testing if a type is `Sized`.
2449 /// Returning true means the type is known to be sized. Returning
2450 /// `false` means nothing -- could be sized, might not be.
2452 /// Note that we could never rely on the fact that a type such as `[_]` is
2453 /// trivially `!Sized` because we could be in a type environment with a
2454 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2455 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2456 /// this method doesn't return `Option<bool>`.
2457 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2459 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2470 | ty::GeneratorWitness(..)
2474 | ty::Error(_) => true,
2476 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2478 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2480 ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(),
2482 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2484 ty::Infer(ty::TyVar(_)) => false,
2487 | ty::Placeholder(..)
2488 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2489 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2494 /// Fast path helper for primitives which are always `Copy` and which
2495 /// have a side-effect-free `Clone` impl.
2497 /// Returning true means the type is known to be pure and `Copy+Clone`.
2498 /// Returning `false` means nothing -- could be `Copy`, might not be.
2500 /// This is mostly useful for optimizations, as there are the types
2501 /// on which we can replace cloning with dereferencing.
2502 pub fn is_trivially_pure_clone_copy(self) -> bool {
2504 ty::Bool | ty::Char | ty::Never => true,
2506 // These aren't even `Clone`
2507 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2509 ty::Int(..) | ty::Uint(..) | ty::Float(..) => true,
2511 // The voldemort ZSTs are fine.
2512 ty::FnDef(..) => true,
2514 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2516 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2517 ty::Tuple(field_tys) => {
2518 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2521 // Sometimes traits aren't implemented for every ABI or arity,
2522 // because we can't be generic over everything yet.
2523 ty::FnPtr(..) => false,
2525 // Definitely absolutely not copy.
2526 ty::Ref(_, _, hir::Mutability::Mut) => false,
2528 // Thin pointers & thin shared references are pure-clone-copy, but for
2529 // anything with custom metadata it might be more complicated.
2530 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2532 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2534 // Might be, but not "trivial" so just giving the safe answer.
2535 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2537 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2539 ty::Bound(..) | ty::Placeholder(..) => {
2540 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2546 /// Extra information about why we ended up with a particular variance.
2547 /// This is only used to add more information to error messages, and
2548 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2549 /// may lead to confusing notes in error messages, it will never cause
2550 /// a miscompilation or unsoundness.
2552 /// When in doubt, use `VarianceDiagInfo::default()`
2553 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2554 pub enum VarianceDiagInfo<'tcx> {
2555 /// No additional information - this is the default.
2556 /// We will not add any additional information to error messages.
2559 /// We switched our variance because a generic argument occurs inside
2560 /// the invariant generic argument of another type.
2562 /// The generic type containing the generic parameter
2563 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2565 /// The index of the generic parameter being used
2566 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2571 impl<'tcx> VarianceDiagInfo<'tcx> {
2572 /// Mirrors `Variance::xform` - used to 'combine' the existing
2573 /// and new `VarianceDiagInfo`s when our variance changes.
2574 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2575 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2577 VarianceDiagInfo::None => other,
2578 VarianceDiagInfo::Invariant { .. } => self,