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, *};
12 self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeFoldable, TypeVisitor,
14 use crate::ty::{DelaySpanBugEmitted, List, ParamEnv};
15 use polonius_engine::Atom;
16 use rustc_data_structures::captures::Captures;
17 use rustc_data_structures::intern::Interned;
19 use rustc_hir::def_id::DefId;
20 use rustc_index::vec::Idx;
21 use rustc_macros::HashStable;
22 use rustc_span::symbol::{kw, Symbol};
23 use rustc_target::abi::VariantIdx;
24 use rustc_target::spec::abi;
26 use std::cmp::Ordering;
28 use std::marker::PhantomData;
29 use std::ops::{ControlFlow, Deref, Range};
30 use ty::util::IntTypeExt;
32 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
33 #[derive(HashStable, TypeFoldable, Lift)]
34 pub struct TypeAndMut<'tcx> {
36 pub mutbl: hir::Mutability,
39 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
41 /// A "free" region `fr` can be interpreted as "some region
42 /// at least as big as the scope `fr.scope`".
43 pub struct FreeRegion {
45 pub bound_region: BoundRegionKind,
48 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
50 pub enum BoundRegionKind {
51 /// An anonymous region parameter for a given fn (&T)
54 /// Named region parameters for functions (a in &'a T)
56 /// The `DefId` is needed to distinguish free regions in
57 /// the event of shadowing.
58 BrNamed(DefId, Symbol),
60 /// Anonymous region for the implicit env pointer parameter
65 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
67 pub struct BoundRegion {
69 pub kind: BoundRegionKind,
72 impl BoundRegionKind {
73 pub fn is_named(&self) -> bool {
75 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
81 /// Defines the kinds of types used by the type system.
83 /// Types written by the user start out as [hir::TyKind](rustc_hir::TyKind) and get
84 /// converted to this representation using `AstConv::ast_ty_to_ty`.
85 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)]
87 #[rustc_diagnostic_item = "TyKind"]
88 pub enum TyKind<'tcx> {
89 /// The primitive boolean type. Written as `bool`.
92 /// The primitive character type; holds a Unicode scalar value
93 /// (a non-surrogate code point). Written as `char`.
96 /// A primitive signed integer type. For example, `i32`.
99 /// A primitive unsigned integer type. For example, `u32`.
102 /// A primitive floating-point type. For example, `f64`.
105 /// Algebraic data types (ADT). For example: structures, enumerations and unions.
107 /// For example, the type `List<i32>` would be represented using the `AdtDef`
108 /// for `struct List<T>` and the substs `[i32]`.
110 /// Note that generic parameters in fields only get lazily substituted
111 /// by using something like `adt_def.all_fields().map(|field| field.ty(tcx, substs))`.
112 Adt(AdtDef<'tcx>, SubstsRef<'tcx>),
114 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
117 /// The pointee of a string slice. Written as `str`.
120 /// An array with the given length. Written as `[T; N]`.
121 Array(Ty<'tcx>, ty::Const<'tcx>),
123 /// The pointee of an array slice. Written as `[T]`.
126 /// A raw pointer. Written as `*mut T` or `*const T`
127 RawPtr(TypeAndMut<'tcx>),
129 /// A reference; a pointer with an associated lifetime. Written as
130 /// `&'a mut T` or `&'a T`.
131 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
133 /// The anonymous type of a function declaration/definition. Each
134 /// function has a unique type.
136 /// For the function `fn foo() -> i32 { 3 }` this type would be
137 /// shown to the user as `fn() -> i32 {foo}`.
139 /// For example the type of `bar` here:
141 /// fn foo() -> i32 { 1 }
142 /// let bar = foo; // bar: fn() -> i32 {foo}
144 FnDef(DefId, SubstsRef<'tcx>),
146 /// A pointer to a function. Written as `fn() -> i32`.
148 /// Note that both functions and closures start out as either
149 /// [FnDef] or [Closure] which can be then be coerced to this variant.
151 /// For example the type of `bar` here:
154 /// fn foo() -> i32 { 1 }
155 /// let bar: fn() -> i32 = foo;
157 FnPtr(PolyFnSig<'tcx>),
159 /// A trait object. Written as `dyn for<'b> Trait<'b, Assoc = u32> + Send + 'a`.
160 Dynamic(&'tcx List<Binder<'tcx, ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
162 /// The anonymous type of a closure. Used to represent the type of `|a| a`.
164 /// Closure substs contain both the - potentially substituted - generic parameters
165 /// of its parent and some synthetic parameters. See the documentation for
166 /// [ClosureSubsts] for more details.
167 Closure(DefId, SubstsRef<'tcx>),
169 /// The anonymous type of a generator. Used to represent the type of
172 /// For more info about generator substs, visit the documentation for
173 /// [GeneratorSubsts].
174 Generator(DefId, SubstsRef<'tcx>, hir::Movability),
176 /// A type representing the types stored inside a generator.
177 /// This should only appear as part of the [GeneratorSubsts].
179 /// Note that the captured variables for generators are stored separately
180 /// using a tuple in the same way as for closures.
182 /// Unlike upvars, the witness can reference lifetimes from
183 /// inside of the generator itself. To deal with them in
184 /// the type of the generator, we convert them to higher ranked
185 /// lifetimes bound by the witness itself.
187 /// Looking at the following example, the witness for this generator
188 /// may end up as something like `for<'a> [Vec<i32>, &'a Vec<i32>]`:
192 /// let x = &vec![3];
197 GeneratorWitness(Binder<'tcx, &'tcx List<Ty<'tcx>>>),
199 /// The never type `!`.
202 /// A tuple type. For example, `(i32, bool)`.
203 Tuple(&'tcx List<Ty<'tcx>>),
205 /// The projection of an associated type. For example,
206 /// `<T as Trait<..>>::N`.
207 Projection(ProjectionTy<'tcx>),
209 /// Opaque (`impl Trait`) type found in a return type.
211 /// The `DefId` comes either from
212 /// * the `impl Trait` ast::Ty node,
213 /// * or the `type Foo = impl Trait` declaration
215 /// For RPIT the substitutions are for the generics of the function,
216 /// while for TAIT it is used for the generic parameters of the alias.
218 /// During codegen, `tcx.type_of(def_id)` can be used to get the underlying type.
219 Opaque(DefId, SubstsRef<'tcx>),
221 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}`.
224 /// Bound type variable, used to represent the `'a` in `for<'a> fn(&'a ())`.
226 /// For canonical queries, we replace inference variables with bound variables,
227 /// so e.g. when checking whether `&'_ (): Trait<_>` holds, we canonicalize that to
228 /// `for<'a, T> &'a (): Trait<T>` and then convert the introduced bound variables
229 /// back to inference variables in a new inference context when inside of the query.
231 /// See the `rustc-dev-guide` for more details about
232 /// [higher-ranked trait bounds][1] and [canonical queries][2].
234 /// [1]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
235 /// [2]: https://rustc-dev-guide.rust-lang.org/traits/canonical-queries.html
236 Bound(ty::DebruijnIndex, BoundTy),
238 /// A placeholder type, used during higher ranked subtyping to instantiate
240 Placeholder(ty::PlaceholderType),
242 /// A type variable used during type checking.
244 /// Similar to placeholders, inference variables also live in a universe to
245 /// correctly deal with higher ranked types. Though unlike placeholders,
246 /// that universe is stored in the `InferCtxt` instead of directly
247 /// inside of the type.
250 /// A placeholder for a type which could not be computed; this is
251 /// propagated to avoid useless error messages.
252 Error(DelaySpanBugEmitted),
255 impl<'tcx> TyKind<'tcx> {
257 pub fn is_primitive(&self) -> bool {
258 matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_))
261 /// Get the article ("a" or "an") to use with this type.
262 pub fn article(&self) -> &'static str {
264 Int(_) | Float(_) | Array(_, _) => "an",
265 Adt(def, _) if def.is_enum() => "an",
266 // This should never happen, but ICEing and causing the user's code
267 // to not compile felt too harsh.
274 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
275 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
276 static_assert_size!(TyKind<'_>, 32);
278 /// A closure can be modeled as a struct that looks like:
280 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
284 /// - 'l0...'li and T0...Tj are the generic parameters
285 /// in scope on the function that defined the closure,
286 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
287 /// is rather hackily encoded via a scalar type. See
288 /// `Ty::to_opt_closure_kind` for details.
289 /// - CS represents the *closure signature*, representing as a `fn()`
290 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
291 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
293 /// - U is a type parameter representing the types of its upvars, tupled up
294 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
295 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
297 /// So, for example, given this function:
299 /// fn foo<'a, T>(data: &'a mut T) {
300 /// do(|| data.count += 1)
303 /// the type of the closure would be something like:
305 /// struct Closure<'a, T, U>(...U);
307 /// Note that the type of the upvar is not specified in the struct.
308 /// You may wonder how the impl would then be able to use the upvar,
309 /// if it doesn't know it's type? The answer is that the impl is
310 /// (conceptually) not fully generic over Closure but rather tied to
311 /// instances with the expected upvar types:
313 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
317 /// You can see that the *impl* fully specified the type of the upvar
318 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
319 /// (Here, I am assuming that `data` is mut-borrowed.)
321 /// Now, the last question you may ask is: Why include the upvar types
322 /// in an extra type parameter? The reason for this design is that the
323 /// upvar types can reference lifetimes that are internal to the
324 /// creating function. In my example above, for example, the lifetime
325 /// `'b` represents the scope of the closure itself; this is some
326 /// subset of `foo`, probably just the scope of the call to the to
327 /// `do()`. If we just had the lifetime/type parameters from the
328 /// enclosing function, we couldn't name this lifetime `'b`. Note that
329 /// there can also be lifetimes in the types of the upvars themselves,
330 /// if one of them happens to be a reference to something that the
331 /// creating fn owns.
333 /// OK, you say, so why not create a more minimal set of parameters
334 /// that just includes the extra lifetime parameters? The answer is
335 /// primarily that it would be hard --- we don't know at the time when
336 /// we create the closure type what the full types of the upvars are,
337 /// nor do we know which are borrowed and which are not. In this
338 /// design, we can just supply a fresh type parameter and figure that
341 /// All right, you say, but why include the type parameters from the
342 /// original function then? The answer is that codegen may need them
343 /// when monomorphizing, and they may not appear in the upvars. A
344 /// closure could capture no variables but still make use of some
345 /// in-scope type parameter with a bound (e.g., if our example above
346 /// had an extra `U: Default`, and the closure called `U::default()`).
348 /// There is another reason. This design (implicitly) prohibits
349 /// closures from capturing themselves (except via a trait
350 /// object). This simplifies closure inference considerably, since it
351 /// means that when we infer the kind of a closure or its upvars, we
352 /// don't have to handle cycles where the decisions we make for
353 /// closure C wind up influencing the decisions we ought to make for
354 /// closure C (which would then require fixed point iteration to
355 /// handle). Plus it fixes an ICE. :P
359 /// Generators are handled similarly in `GeneratorSubsts`. The set of
360 /// type parameters is similar, but `CK` and `CS` are replaced by the
361 /// following type parameters:
363 /// * `GS`: The generator's "resume type", which is the type of the
364 /// argument passed to `resume`, and the type of `yield` expressions
365 /// inside the generator.
366 /// * `GY`: The "yield type", which is the type of values passed to
367 /// `yield` inside the generator.
368 /// * `GR`: The "return type", which is the type of value returned upon
369 /// completion of the generator.
370 /// * `GW`: The "generator witness".
371 #[derive(Copy, Clone, Debug, TypeFoldable)]
372 pub struct ClosureSubsts<'tcx> {
373 /// Lifetime and type parameters from the enclosing function,
374 /// concatenated with a tuple containing the types of the upvars.
376 /// These are separated out because codegen wants to pass them around
377 /// when monomorphizing.
378 pub substs: SubstsRef<'tcx>,
381 /// Struct returned by `split()`.
382 pub struct ClosureSubstsParts<'tcx, T> {
383 pub parent_substs: &'tcx [GenericArg<'tcx>],
384 pub closure_kind_ty: T,
385 pub closure_sig_as_fn_ptr_ty: T,
386 pub tupled_upvars_ty: T,
389 impl<'tcx> ClosureSubsts<'tcx> {
390 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
391 /// for the closure parent, alongside additional closure-specific components.
394 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
395 ) -> ClosureSubsts<'tcx> {
397 substs: tcx.mk_substs(
398 parts.parent_substs.iter().copied().chain(
399 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
401 .map(|&ty| ty.into()),
407 /// Divides the closure substs into their respective components.
408 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
409 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
410 match self.substs[..] {
412 ref parent_substs @ ..,
414 closure_sig_as_fn_ptr_ty,
416 ] => ClosureSubstsParts {
419 closure_sig_as_fn_ptr_ty,
422 _ => bug!("closure substs missing synthetics"),
426 /// Returns `true` only if enough of the synthetic types are known to
427 /// allow using all of the methods on `ClosureSubsts` without panicking.
429 /// Used primarily by `ty::print::pretty` to be able to handle closure
430 /// types that haven't had their synthetic types substituted in.
431 pub fn is_valid(self) -> bool {
432 self.substs.len() >= 3
433 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
436 /// Returns the substitutions of the closure's parent.
437 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
438 self.split().parent_substs
441 /// Returns an iterator over the list of types of captured paths by the closure.
442 /// In case there was a type error in figuring out the types of the captured path, an
443 /// empty iterator is returned.
445 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
446 match self.tupled_upvars_ty().kind() {
447 TyKind::Error(_) => None,
448 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
449 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
450 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
456 /// Returns the tuple type representing the upvars for this closure.
458 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
459 self.split().tupled_upvars_ty.expect_ty()
462 /// Returns the closure kind for this closure; may return a type
463 /// variable during inference. To get the closure kind during
464 /// inference, use `infcx.closure_kind(substs)`.
465 pub fn kind_ty(self) -> Ty<'tcx> {
466 self.split().closure_kind_ty.expect_ty()
469 /// Returns the `fn` pointer type representing the closure signature for this
471 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
472 // type is known at the time of the creation of `ClosureSubsts`,
473 // see `rustc_typeck::check::closure`.
474 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
475 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
478 /// Returns the closure kind for this closure; only usable outside
479 /// of an inference context, because in that context we know that
480 /// there are no type variables.
482 /// If you have an inference context, use `infcx.closure_kind()`.
483 pub fn kind(self) -> ty::ClosureKind {
484 self.kind_ty().to_opt_closure_kind().unwrap()
487 /// Extracts the signature from the closure.
488 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
489 let ty = self.sig_as_fn_ptr_ty();
491 ty::FnPtr(sig) => *sig,
492 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
497 /// Similar to `ClosureSubsts`; see the above documentation for more.
498 #[derive(Copy, Clone, Debug, TypeFoldable)]
499 pub struct GeneratorSubsts<'tcx> {
500 pub substs: SubstsRef<'tcx>,
503 pub struct GeneratorSubstsParts<'tcx, T> {
504 pub parent_substs: &'tcx [GenericArg<'tcx>],
509 pub tupled_upvars_ty: T,
512 impl<'tcx> GeneratorSubsts<'tcx> {
513 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
514 /// for the generator parent, alongside additional generator-specific components.
517 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
518 ) -> GeneratorSubsts<'tcx> {
520 substs: tcx.mk_substs(
521 parts.parent_substs.iter().copied().chain(
527 parts.tupled_upvars_ty,
530 .map(|&ty| ty.into()),
536 /// Divides the generator substs into their respective components.
537 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
538 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
539 match self.substs[..] {
540 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
541 GeneratorSubstsParts {
550 _ => bug!("generator substs missing synthetics"),
554 /// Returns `true` only if enough of the synthetic types are known to
555 /// allow using all of the methods on `GeneratorSubsts` without panicking.
557 /// Used primarily by `ty::print::pretty` to be able to handle generator
558 /// types that haven't had their synthetic types substituted in.
559 pub fn is_valid(self) -> bool {
560 self.substs.len() >= 5
561 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
564 /// Returns the substitutions of the generator's parent.
565 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
566 self.split().parent_substs
569 /// This describes the types that can be contained in a generator.
570 /// It will be a type variable initially and unified in the last stages of typeck of a body.
571 /// It contains a tuple of all the types that could end up on a generator frame.
572 /// The state transformation MIR pass may only produce layouts which mention types
573 /// in this tuple. Upvars are not counted here.
574 pub fn witness(self) -> Ty<'tcx> {
575 self.split().witness.expect_ty()
578 /// Returns an iterator over the list of types of captured paths by the generator.
579 /// In case there was a type error in figuring out the types of the captured path, an
580 /// empty iterator is returned.
582 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
583 match self.tupled_upvars_ty().kind() {
584 TyKind::Error(_) => None,
585 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
586 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
587 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
593 /// Returns the tuple type representing the upvars for this generator.
595 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
596 self.split().tupled_upvars_ty.expect_ty()
599 /// Returns the type representing the resume type of the generator.
600 pub fn resume_ty(self) -> Ty<'tcx> {
601 self.split().resume_ty.expect_ty()
604 /// Returns the type representing the yield type of the generator.
605 pub fn yield_ty(self) -> Ty<'tcx> {
606 self.split().yield_ty.expect_ty()
609 /// Returns the type representing the return type of the generator.
610 pub fn return_ty(self) -> Ty<'tcx> {
611 self.split().return_ty.expect_ty()
614 /// Returns the "generator signature", which consists of its yield
615 /// and return types.
617 /// N.B., some bits of the code prefers to see this wrapped in a
618 /// binder, but it never contains bound regions. Probably this
619 /// function should be removed.
620 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
621 ty::Binder::dummy(self.sig())
624 /// Returns the "generator signature", which consists of its resume, yield
625 /// and return types.
626 pub fn sig(self) -> GenSig<'tcx> {
628 resume_ty: self.resume_ty(),
629 yield_ty: self.yield_ty(),
630 return_ty: self.return_ty(),
635 impl<'tcx> GeneratorSubsts<'tcx> {
636 /// Generator has not been resumed yet.
637 pub const UNRESUMED: usize = 0;
638 /// Generator has returned or is completed.
639 pub const RETURNED: usize = 1;
640 /// Generator has been poisoned.
641 pub const POISONED: usize = 2;
643 const UNRESUMED_NAME: &'static str = "Unresumed";
644 const RETURNED_NAME: &'static str = "Returned";
645 const POISONED_NAME: &'static str = "Panicked";
647 /// The valid variant indices of this generator.
649 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
650 // FIXME requires optimized MIR
651 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
652 VariantIdx::new(0)..VariantIdx::new(num_variants)
655 /// The discriminant for the given variant. Panics if the `variant_index` is
658 pub fn discriminant_for_variant(
662 variant_index: VariantIdx,
664 // Generators don't support explicit discriminant values, so they are
665 // the same as the variant index.
666 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
667 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
670 /// The set of all discriminants for the generator, enumerated with their
673 pub fn discriminants(
677 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
678 self.variant_range(def_id, tcx).map(move |index| {
679 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
683 /// Calls `f` with a reference to the name of the enumerator for the given
685 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
687 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
688 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
689 Self::POISONED => Cow::from(Self::POISONED_NAME),
690 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
694 /// The type of the state discriminant used in the generator type.
696 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
700 /// This returns the types of the MIR locals which had to be stored across suspension points.
701 /// It is calculated in rustc_mir_transform::generator::StateTransform.
702 /// All the types here must be in the tuple in GeneratorInterior.
704 /// The locals are grouped by their variant number. Note that some locals may
705 /// be repeated in multiple variants.
711 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
712 let layout = tcx.generator_layout(def_id).unwrap();
713 layout.variant_fields.iter().map(move |variant| {
714 variant.iter().map(move |field| layout.field_tys[*field].subst(tcx, self.substs))
718 /// This is the types of the fields of a generator which are not stored in a
721 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
726 #[derive(Debug, Copy, Clone, HashStable)]
727 pub enum UpvarSubsts<'tcx> {
728 Closure(SubstsRef<'tcx>),
729 Generator(SubstsRef<'tcx>),
732 impl<'tcx> UpvarSubsts<'tcx> {
733 /// Returns an iterator over the list of types of captured paths by the closure/generator.
734 /// In case there was a type error in figuring out the types of the captured path, an
735 /// empty iterator is returned.
737 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
738 let tupled_tys = match self {
739 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
740 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
743 match tupled_tys.kind() {
744 TyKind::Error(_) => None,
745 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
746 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
747 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
754 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
756 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
757 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
762 /// An inline const is modeled like
764 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
768 /// - 'l0...'li and T0...Tj are the generic parameters
769 /// inherited from the item that defined the inline const,
770 /// - R represents the type of the constant.
772 /// When the inline const is instantiated, `R` is substituted as the actual inferred
773 /// type of the constant. The reason that `R` is represented as an extra type parameter
774 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
775 /// inline const can reference lifetimes that are internal to the creating function.
776 #[derive(Copy, Clone, Debug, TypeFoldable)]
777 pub struct InlineConstSubsts<'tcx> {
778 /// Generic parameters from the enclosing item,
779 /// concatenated with the inferred type of the constant.
780 pub substs: SubstsRef<'tcx>,
783 /// Struct returned by `split()`.
784 pub struct InlineConstSubstsParts<'tcx, T> {
785 pub parent_substs: &'tcx [GenericArg<'tcx>],
789 impl<'tcx> InlineConstSubsts<'tcx> {
790 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
793 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
794 ) -> InlineConstSubsts<'tcx> {
796 substs: tcx.mk_substs(
797 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
802 /// Divides the inline const substs into their respective components.
803 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
804 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
805 match self.substs[..] {
806 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
807 _ => bug!("inline const substs missing synthetics"),
811 /// Returns the substitutions of the inline const's parent.
812 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
813 self.split().parent_substs
816 /// Returns the type of this inline const.
817 pub fn ty(self) -> Ty<'tcx> {
818 self.split().ty.expect_ty()
822 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
823 #[derive(HashStable, TypeFoldable)]
824 pub enum ExistentialPredicate<'tcx> {
825 /// E.g., `Iterator`.
826 Trait(ExistentialTraitRef<'tcx>),
827 /// E.g., `Iterator::Item = T`.
828 Projection(ExistentialProjection<'tcx>),
833 impl<'tcx> ExistentialPredicate<'tcx> {
834 /// Compares via an ordering that will not change if modules are reordered or other changes are
835 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
836 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
837 use self::ExistentialPredicate::*;
838 match (*self, *other) {
839 (Trait(_), Trait(_)) => Ordering::Equal,
840 (Projection(ref a), Projection(ref b)) => {
841 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
843 (AutoTrait(ref a), AutoTrait(ref b)) => {
844 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
846 (Trait(_), _) => Ordering::Less,
847 (Projection(_), Trait(_)) => Ordering::Greater,
848 (Projection(_), _) => Ordering::Less,
849 (AutoTrait(_), _) => Ordering::Greater,
854 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
855 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
856 use crate::ty::ToPredicate;
857 match self.skip_binder() {
858 ExistentialPredicate::Trait(tr) => {
859 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
861 ExistentialPredicate::Projection(p) => {
862 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
864 ExistentialPredicate::AutoTrait(did) => {
865 let trait_ref = self.rebind(ty::TraitRef {
867 substs: tcx.mk_substs_trait(self_ty, &[]),
869 trait_ref.without_const().to_predicate(tcx)
875 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
876 /// Returns the "principal `DefId`" of this set of existential predicates.
878 /// A Rust trait object type consists (in addition to a lifetime bound)
879 /// of a set of trait bounds, which are separated into any number
880 /// of auto-trait bounds, and at most one non-auto-trait bound. The
881 /// non-auto-trait bound is called the "principal" of the trait
884 /// Only the principal can have methods or type parameters (because
885 /// auto traits can have neither of them). This is important, because
886 /// it means the auto traits can be treated as an unordered set (methods
887 /// would force an order for the vtable, while relating traits with
888 /// type parameters without knowing the order to relate them in is
889 /// a rather non-trivial task).
891 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
892 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
893 /// are the set `{Sync}`.
895 /// It is also possible to have a "trivial" trait object that
896 /// consists only of auto traits, with no principal - for example,
897 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
898 /// is `{Send, Sync}`, while there is no principal. These trait objects
899 /// have a "trivial" vtable consisting of just the size, alignment,
901 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
903 .map_bound(|this| match this {
904 ExistentialPredicate::Trait(tr) => Some(tr),
910 pub fn principal_def_id(&self) -> Option<DefId> {
911 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
915 pub fn projection_bounds<'a>(
917 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
918 self.iter().filter_map(|predicate| {
920 .map_bound(|pred| match pred {
921 ExistentialPredicate::Projection(projection) => Some(projection),
929 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
930 self.iter().filter_map(|predicate| match predicate.skip_binder() {
931 ExistentialPredicate::AutoTrait(did) => Some(did),
937 /// A complete reference to a trait. These take numerous guises in syntax,
938 /// but perhaps the most recognizable form is in a where-clause:
942 /// This would be represented by a trait-reference where the `DefId` is the
943 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
944 /// and `U` as parameter 1.
946 /// Trait references also appear in object types like `Foo<U>`, but in
947 /// that case the `Self` parameter is absent from the substitutions.
948 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
949 #[derive(HashStable, TypeFoldable)]
950 pub struct TraitRef<'tcx> {
952 pub substs: SubstsRef<'tcx>,
955 impl<'tcx> TraitRef<'tcx> {
956 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
957 TraitRef { def_id, substs }
960 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
961 /// are the parameters defined on trait.
962 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
963 ty::Binder::dummy(TraitRef {
965 substs: InternalSubsts::identity_for_item(tcx, def_id),
970 pub fn self_ty(&self) -> Ty<'tcx> {
971 self.substs.type_at(0)
977 substs: SubstsRef<'tcx>,
978 ) -> ty::TraitRef<'tcx> {
979 let defs = tcx.generics_of(trait_id);
980 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
984 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
986 impl<'tcx> PolyTraitRef<'tcx> {
987 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
988 self.map_bound_ref(|tr| tr.self_ty())
991 pub fn def_id(&self) -> DefId {
992 self.skip_binder().def_id
995 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
996 self.map_bound(|trait_ref| ty::TraitPredicate {
998 constness: ty::BoundConstness::NotConst,
999 polarity: ty::ImplPolarity::Positive,
1003 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
1004 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
1005 self.map_bound(|trait_ref| ty::TraitPredicate {
1007 constness: ty::BoundConstness::NotConst,
1008 polarity: ty::ImplPolarity::Negative,
1013 /// An existential reference to a trait, where `Self` is erased.
1014 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
1016 /// exists T. T: Trait<'a, 'b, X, Y>
1018 /// The substitutions don't include the erased `Self`, only trait
1019 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
1020 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1021 #[derive(HashStable, TypeFoldable)]
1022 pub struct ExistentialTraitRef<'tcx> {
1024 pub substs: SubstsRef<'tcx>,
1027 impl<'tcx> ExistentialTraitRef<'tcx> {
1028 pub fn erase_self_ty(
1030 trait_ref: ty::TraitRef<'tcx>,
1031 ) -> ty::ExistentialTraitRef<'tcx> {
1032 // Assert there is a Self.
1033 trait_ref.substs.type_at(0);
1035 ty::ExistentialTraitRef {
1036 def_id: trait_ref.def_id,
1037 substs: tcx.intern_substs(&trait_ref.substs[1..]),
1041 /// Object types don't have a self type specified. Therefore, when
1042 /// we convert the principal trait-ref into a normal trait-ref,
1043 /// you must give *some* self type. A common choice is `mk_err()`
1044 /// or some placeholder type.
1045 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
1046 // otherwise the escaping vars would be captured by the binder
1047 // debug_assert!(!self_ty.has_escaping_bound_vars());
1049 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
1053 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
1055 impl<'tcx> PolyExistentialTraitRef<'tcx> {
1056 pub fn def_id(&self) -> DefId {
1057 self.skip_binder().def_id
1060 /// Object types don't have a self type specified. Therefore, when
1061 /// we convert the principal trait-ref into a normal trait-ref,
1062 /// you must give *some* self type. A common choice is `mk_err()`
1063 /// or some placeholder type.
1064 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
1065 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
1069 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1070 #[derive(HashStable)]
1071 pub enum BoundVariableKind {
1073 Region(BoundRegionKind),
1077 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
1078 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
1079 /// (which would be represented by the type `PolyTraitRef ==
1080 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
1081 /// erase, or otherwise "discharge" these bound vars, we change the
1082 /// type from `Binder<'tcx, T>` to just `T` (see
1083 /// e.g., `liberate_late_bound_regions`).
1085 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
1086 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1087 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
1089 impl<'tcx, T> Binder<'tcx, T>
1091 T: TypeFoldable<'tcx>,
1093 /// Wraps `value` in a binder, asserting that `value` does not
1094 /// contain any bound vars that would be bound by the
1095 /// binder. This is commonly used to 'inject' a value T into a
1096 /// different binding level.
1097 pub fn dummy(value: T) -> Binder<'tcx, T> {
1098 assert!(!value.has_escaping_bound_vars());
1099 Binder(value, ty::List::empty())
1102 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
1103 if cfg!(debug_assertions) {
1104 let mut validator = ValidateBoundVars::new(vars);
1105 value.visit_with(&mut validator);
1111 impl<'tcx, T> Binder<'tcx, T> {
1112 /// Skips the binder and returns the "bound" value. This is a
1113 /// risky thing to do because it's easy to get confused about
1114 /// De Bruijn indices and the like. It is usually better to
1115 /// discharge the binder using `no_bound_vars` or
1116 /// `replace_late_bound_regions` or something like
1117 /// that. `skip_binder` is only valid when you are either
1118 /// extracting data that has nothing to do with bound vars, you
1119 /// are doing some sort of test that does not involve bound
1120 /// regions, or you are being very careful about your depth
1123 /// Some examples where `skip_binder` is reasonable:
1125 /// - extracting the `DefId` from a PolyTraitRef;
1126 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1127 /// a type parameter `X`, since the type `X` does not reference any regions
1128 pub fn skip_binder(self) -> T {
1132 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1136 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1137 Binder(&self.0, self.1)
1140 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1144 let value = f(&self.0);
1145 Binder(value, self.1)
1148 pub fn map_bound_ref<F, U: TypeFoldable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1152 self.as_ref().map_bound(f)
1155 pub fn map_bound<F, U: TypeFoldable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1159 let value = f(self.0);
1160 if cfg!(debug_assertions) {
1161 let mut validator = ValidateBoundVars::new(self.1);
1162 value.visit_with(&mut validator);
1164 Binder(value, self.1)
1167 pub fn try_map_bound<F, U: TypeFoldable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1169 F: FnOnce(T) -> Result<U, E>,
1171 let value = f(self.0)?;
1172 if cfg!(debug_assertions) {
1173 let mut validator = ValidateBoundVars::new(self.1);
1174 value.visit_with(&mut validator);
1176 Ok(Binder(value, self.1))
1179 /// Wraps a `value` in a binder, using the same bound variables as the
1180 /// current `Binder`. This should not be used if the new value *changes*
1181 /// the bound variables. Note: the (old or new) value itself does not
1182 /// necessarily need to *name* all the bound variables.
1184 /// This currently doesn't do anything different than `bind`, because we
1185 /// don't actually track bound vars. However, semantically, it is different
1186 /// because bound vars aren't allowed to change here, whereas they are
1187 /// in `bind`. This may be (debug) asserted in the future.
1188 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1190 U: TypeFoldable<'tcx>,
1192 if cfg!(debug_assertions) {
1193 let mut validator = ValidateBoundVars::new(self.bound_vars());
1194 value.visit_with(&mut validator);
1196 Binder(value, self.1)
1199 /// Unwraps and returns the value within, but only if it contains
1200 /// no bound vars at all. (In other words, if this binder --
1201 /// and indeed any enclosing binder -- doesn't bind anything at
1202 /// all.) Otherwise, returns `None`.
1204 /// (One could imagine having a method that just unwraps a single
1205 /// binder, but permits late-bound vars bound by enclosing
1206 /// binders, but that would require adjusting the debruijn
1207 /// indices, and given the shallow binding structure we often use,
1208 /// would not be that useful.)
1209 pub fn no_bound_vars(self) -> Option<T>
1211 T: TypeFoldable<'tcx>,
1213 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1216 /// Splits the contents into two things that share the same binder
1217 /// level as the original, returning two distinct binders.
1219 /// `f` should consider bound regions at depth 1 to be free, and
1220 /// anything it produces with bound regions at depth 1 will be
1221 /// bound in the resulting return values.
1222 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1224 F: FnOnce(T) -> (U, V),
1226 let (u, v) = f(self.0);
1227 (Binder(u, self.1), Binder(v, self.1))
1231 impl<'tcx, T> Binder<'tcx, Option<T>> {
1232 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1233 let bound_vars = self.1;
1234 self.0.map(|v| Binder(v, bound_vars))
1238 /// Represents the projection of an associated type. In explicit UFCS
1239 /// form this would be written `<T as Trait<..>>::N`.
1240 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1241 #[derive(HashStable, TypeFoldable)]
1242 pub struct ProjectionTy<'tcx> {
1243 /// The parameters of the associated item.
1244 pub substs: SubstsRef<'tcx>,
1246 /// The `DefId` of the `TraitItem` for the associated type `N`.
1248 /// Note that this is not the `DefId` of the `TraitRef` containing this
1249 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
1250 pub item_def_id: DefId,
1253 impl<'tcx> ProjectionTy<'tcx> {
1254 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1255 tcx.associated_item(self.item_def_id).container.id()
1258 /// Extracts the underlying trait reference and own substs from this projection.
1259 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1260 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1261 pub fn trait_ref_and_own_substs(
1264 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1265 let def_id = tcx.associated_item(self.item_def_id).container.id();
1266 let trait_generics = tcx.generics_of(def_id);
1268 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1269 &self.substs[trait_generics.count()..],
1273 /// Extracts the underlying trait reference from this projection.
1274 /// For example, if this is a projection of `<T as Iterator>::Item`,
1275 /// then this function would return a `T: Iterator` trait reference.
1277 /// WARNING: This will drop the substs for generic associated types
1278 /// consider calling [Self::trait_ref_and_own_substs] to get those
1280 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1281 let def_id = self.trait_def_id(tcx);
1282 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1285 pub fn self_ty(&self) -> Ty<'tcx> {
1286 self.substs.type_at(0)
1290 #[derive(Copy, Clone, Debug, TypeFoldable)]
1291 pub struct GenSig<'tcx> {
1292 pub resume_ty: Ty<'tcx>,
1293 pub yield_ty: Ty<'tcx>,
1294 pub return_ty: Ty<'tcx>,
1297 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1299 /// Signature of a function type, which we have arbitrarily
1300 /// decided to use to refer to the input/output types.
1302 /// - `inputs`: is the list of arguments and their modes.
1303 /// - `output`: is the return type.
1304 /// - `c_variadic`: indicates whether this is a C-variadic function.
1305 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1306 #[derive(HashStable, TypeFoldable)]
1307 pub struct FnSig<'tcx> {
1308 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1309 pub c_variadic: bool,
1310 pub unsafety: hir::Unsafety,
1314 impl<'tcx> FnSig<'tcx> {
1315 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1316 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1319 pub fn output(&self) -> Ty<'tcx> {
1320 self.inputs_and_output[self.inputs_and_output.len() - 1]
1323 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1325 fn fake() -> FnSig<'tcx> {
1327 inputs_and_output: List::empty(),
1329 unsafety: hir::Unsafety::Normal,
1330 abi: abi::Abi::Rust,
1335 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1337 impl<'tcx> PolyFnSig<'tcx> {
1339 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1340 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1343 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1344 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1346 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1347 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1350 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1351 self.map_bound_ref(|fn_sig| fn_sig.output())
1353 pub fn c_variadic(&self) -> bool {
1354 self.skip_binder().c_variadic
1356 pub fn unsafety(&self) -> hir::Unsafety {
1357 self.skip_binder().unsafety
1359 pub fn abi(&self) -> abi::Abi {
1360 self.skip_binder().abi
1364 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1366 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1367 #[derive(HashStable)]
1368 pub struct ParamTy {
1373 impl<'tcx> ParamTy {
1374 pub fn new(index: u32, name: Symbol) -> ParamTy {
1375 ParamTy { index, name }
1378 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1379 ParamTy::new(def.index, def.name)
1383 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1384 tcx.mk_ty_param(self.index, self.name)
1388 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1389 #[derive(HashStable)]
1390 pub struct ParamConst {
1396 pub fn new(index: u32, name: Symbol) -> ParamConst {
1397 ParamConst { index, name }
1400 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1401 ParamConst::new(def.index, def.name)
1405 /// Use this rather than `TyKind`, whenever possible.
1406 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1407 #[rustc_pass_by_value]
1408 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind>);
1410 impl<'tcx> Deref for Region<'tcx> {
1411 type Target = RegionKind;
1413 fn deref(&self) -> &RegionKind {
1418 impl<'tcx> fmt::Debug for Region<'tcx> {
1419 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1420 write!(f, "{:?}", self.kind())
1424 /// Representation of regions. Note that the NLL checker uses a distinct
1425 /// representation of regions. For this reason, it internally replaces all the
1426 /// regions with inference variables -- the index of the variable is then used
1427 /// to index into internal NLL data structures. See `rustc_const_eval::borrow_check`
1428 /// module for more information.
1430 /// Note: operations are on the wrapper `Region` type, which is interned,
1431 /// rather than this type.
1433 /// ## The Region lattice within a given function
1435 /// In general, the region lattice looks like
1438 /// static ----------+-----...------+ (greatest)
1440 /// early-bound and | |
1441 /// free regions | |
1444 /// empty(root) placeholder(U1) |
1446 /// | / placeholder(Un)
1451 /// empty(Un) -------- (smallest)
1454 /// Early-bound/free regions are the named lifetimes in scope from the
1455 /// function declaration. They have relationships to one another
1456 /// determined based on the declared relationships from the
1459 /// Note that inference variables and bound regions are not included
1460 /// in this diagram. In the case of inference variables, they should
1461 /// be inferred to some other region from the diagram. In the case of
1462 /// bound regions, they are excluded because they don't make sense to
1463 /// include -- the diagram indicates the relationship between free
1466 /// ## Inference variables
1468 /// During region inference, we sometimes create inference variables,
1469 /// represented as `ReVar`. These will be inferred by the code in
1470 /// `infer::lexical_region_resolve` to some free region from the
1471 /// lattice above (the minimal region that meets the
1474 /// During NLL checking, where regions are defined differently, we
1475 /// also use `ReVar` -- in that case, the index is used to index into
1476 /// the NLL region checker's data structures. The variable may in fact
1477 /// represent either a free region or an inference variable, in that
1480 /// ## Bound Regions
1482 /// These are regions that are stored behind a binder and must be substituted
1483 /// with some concrete region before being used. There are two kind of
1484 /// bound regions: early-bound, which are bound in an item's `Generics`,
1485 /// and are substituted by an `InternalSubsts`, and late-bound, which are part of
1486 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1487 /// the likes of `liberate_late_bound_regions`. The distinction exists
1488 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1490 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1491 /// outside their binder, e.g., in types passed to type inference, and
1492 /// should first be substituted (by placeholder regions, free regions,
1493 /// or region variables).
1495 /// ## Placeholder and Free Regions
1497 /// One often wants to work with bound regions without knowing their precise
1498 /// identity. For example, when checking a function, the lifetime of a borrow
1499 /// can end up being assigned to some region parameter. In these cases,
1500 /// it must be ensured that bounds on the region can't be accidentally
1501 /// assumed without being checked.
1503 /// To do this, we replace the bound regions with placeholder markers,
1504 /// which don't satisfy any relation not explicitly provided.
1506 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1507 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1508 /// to be used. These also support explicit bounds: both the internally-stored
1509 /// *scope*, which the region is assumed to outlive, as well as other
1510 /// relations stored in the `FreeRegionMap`. Note that these relations
1511 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1512 /// `resolve_regions_and_report_errors`.
1514 /// When working with higher-ranked types, some region relations aren't
1515 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1516 /// `RePlaceholder` is designed for this purpose. In these contexts,
1517 /// there's also the risk that some inference variable laying around will
1518 /// get unified with your placeholder region: if you want to check whether
1519 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1520 /// with a placeholder region `'%a`, the variable `'_` would just be
1521 /// instantiated to the placeholder region `'%a`, which is wrong because
1522 /// the inference variable is supposed to satisfy the relation
1523 /// *for every value of the placeholder region*. To ensure that doesn't
1524 /// happen, you can use `leak_check`. This is more clearly explained
1525 /// by the [rustc dev guide].
1527 /// [1]: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1528 /// [2]: https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1529 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
1530 #[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)]
1531 pub enum RegionKind {
1532 /// Region bound in a type or fn declaration which will be
1533 /// substituted 'early' -- that is, at the same time when type
1534 /// parameters are substituted.
1535 ReEarlyBound(EarlyBoundRegion),
1537 /// Region bound in a function scope, which will be substituted when the
1538 /// function is called.
1539 ReLateBound(ty::DebruijnIndex, BoundRegion),
1541 /// When checking a function body, the types of all arguments and so forth
1542 /// that refer to bound region parameters are modified to refer to free
1543 /// region parameters.
1546 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1549 /// A region variable. Should not exist outside of type inference.
1552 /// A placeholder region -- basically, the higher-ranked version of `ReFree`.
1553 /// Should not exist outside of type inference.
1554 RePlaceholder(ty::PlaceholderRegion),
1556 /// Empty lifetime is for data that is never accessed. We tag the
1557 /// empty lifetime with a universe -- the idea is that we don't
1558 /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable.
1559 /// Therefore, the `'empty` in a universe `U` is less than all
1560 /// regions visible from `U`, but not less than regions not visible
1562 ReEmpty(ty::UniverseIndex),
1564 /// Erased region, used by trait selection, in MIR and during codegen.
1568 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
1569 pub struct EarlyBoundRegion {
1575 /// A **`const`** **v**ariable **ID**.
1576 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1577 pub struct ConstVid<'tcx> {
1579 pub phantom: PhantomData<&'tcx ()>,
1582 rustc_index::newtype_index! {
1583 /// A **region** (lifetime) **v**ariable **ID**.
1584 pub struct RegionVid {
1585 DEBUG_FORMAT = custom,
1589 impl Atom for RegionVid {
1590 fn index(self) -> usize {
1595 rustc_index::newtype_index! {
1596 pub struct BoundVar { .. }
1599 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1600 #[derive(HashStable)]
1601 pub struct BoundTy {
1603 pub kind: BoundTyKind,
1606 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1607 #[derive(HashStable)]
1608 pub enum BoundTyKind {
1613 impl From<BoundVar> for BoundTy {
1614 fn from(var: BoundVar) -> Self {
1615 BoundTy { var, kind: BoundTyKind::Anon }
1619 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1620 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1621 #[derive(HashStable, TypeFoldable)]
1622 pub struct ExistentialProjection<'tcx> {
1623 pub item_def_id: DefId,
1624 pub substs: SubstsRef<'tcx>,
1625 pub term: Term<'tcx>,
1628 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1630 impl<'tcx> ExistentialProjection<'tcx> {
1631 /// Extracts the underlying existential trait reference from this projection.
1632 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1633 /// then this function would return an `exists T. T: Iterator` existential trait
1635 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1636 let def_id = tcx.associated_item(self.item_def_id).container.id();
1637 let subst_count = tcx.generics_of(def_id).count() - 1;
1638 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1639 ty::ExistentialTraitRef { def_id, substs }
1642 pub fn with_self_ty(
1646 ) -> ty::ProjectionPredicate<'tcx> {
1647 // otherwise the escaping regions would be captured by the binders
1648 debug_assert!(!self_ty.has_escaping_bound_vars());
1650 ty::ProjectionPredicate {
1651 projection_ty: ty::ProjectionTy {
1652 item_def_id: self.item_def_id,
1653 substs: tcx.mk_substs_trait(self_ty, self.substs),
1659 pub fn erase_self_ty(
1661 projection_predicate: ty::ProjectionPredicate<'tcx>,
1663 // Assert there is a Self.
1664 projection_predicate.projection_ty.substs.type_at(0);
1667 item_def_id: projection_predicate.projection_ty.item_def_id,
1668 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1669 term: projection_predicate.term,
1674 impl<'tcx> PolyExistentialProjection<'tcx> {
1675 pub fn with_self_ty(
1679 ) -> ty::PolyProjectionPredicate<'tcx> {
1680 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1683 pub fn item_def_id(&self) -> DefId {
1684 self.skip_binder().item_def_id
1688 /// Region utilities
1689 impl<'tcx> Region<'tcx> {
1690 pub fn kind(self) -> RegionKind {
1694 /// Is this region named by the user?
1695 pub fn has_name(self) -> bool {
1697 ty::ReEarlyBound(ebr) => ebr.has_name(),
1698 ty::ReLateBound(_, br) => br.kind.is_named(),
1699 ty::ReFree(fr) => fr.bound_region.is_named(),
1700 ty::ReStatic => true,
1701 ty::ReVar(..) => false,
1702 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1703 ty::ReEmpty(_) => false,
1704 ty::ReErased => false,
1709 pub fn is_static(self) -> bool {
1710 matches!(*self, ty::ReStatic)
1714 pub fn is_erased(self) -> bool {
1715 matches!(*self, ty::ReErased)
1719 pub fn is_late_bound(self) -> bool {
1720 matches!(*self, ty::ReLateBound(..))
1724 pub fn is_placeholder(self) -> bool {
1725 matches!(*self, ty::RePlaceholder(..))
1729 pub fn is_empty(self) -> bool {
1730 matches!(*self, ty::ReEmpty(..))
1734 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1736 ty::ReLateBound(debruijn, _) => debruijn >= index,
1741 pub fn type_flags(self) -> TypeFlags {
1742 let mut flags = TypeFlags::empty();
1746 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1747 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1748 flags = flags | TypeFlags::HAS_RE_INFER;
1750 ty::RePlaceholder(..) => {
1751 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1752 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1753 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1755 ty::ReEarlyBound(..) => {
1756 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1757 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1758 flags = flags | TypeFlags::HAS_RE_PARAM;
1760 ty::ReFree { .. } => {
1761 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1762 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1764 ty::ReEmpty(_) | ty::ReStatic => {
1765 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1767 ty::ReLateBound(..) => {
1768 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1771 flags = flags | TypeFlags::HAS_RE_ERASED;
1775 debug!("type_flags({:?}) = {:?}", self, flags);
1780 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1781 /// For example, consider the regions in this snippet of code:
1785 /// ^^ -- early bound, declared on an impl
1787 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1788 /// ^^ ^^ ^ anonymous, late-bound
1789 /// | early-bound, appears in where-clauses
1790 /// late-bound, appears only in fn args
1795 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1796 /// of the impl, and for all the other highlighted regions, it
1797 /// would return the `DefId` of the function. In other cases (not shown), this
1798 /// function might return the `DefId` of a closure.
1799 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1801 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1802 ty::ReFree(fr) => fr.scope,
1803 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1809 impl<'tcx> Ty<'tcx> {
1811 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1816 pub fn flags(self) -> TypeFlags {
1821 pub fn is_unit(self) -> bool {
1823 Tuple(ref tys) => tys.is_empty(),
1829 pub fn is_never(self) -> bool {
1830 matches!(self.kind(), Never)
1834 pub fn is_primitive(self) -> bool {
1835 self.kind().is_primitive()
1839 pub fn is_adt(self) -> bool {
1840 matches!(self.kind(), Adt(..))
1844 pub fn is_ref(self) -> bool {
1845 matches!(self.kind(), Ref(..))
1849 pub fn is_ty_var(self) -> bool {
1850 matches!(self.kind(), Infer(TyVar(_)))
1854 pub fn ty_vid(self) -> Option<ty::TyVid> {
1856 &Infer(TyVar(vid)) => Some(vid),
1862 pub fn is_ty_infer(self) -> bool {
1863 matches!(self.kind(), Infer(_))
1867 pub fn is_phantom_data(self) -> bool {
1868 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1872 pub fn is_bool(self) -> bool {
1873 *self.kind() == Bool
1876 /// Returns `true` if this type is a `str`.
1878 pub fn is_str(self) -> bool {
1883 pub fn is_param(self, index: u32) -> bool {
1885 ty::Param(ref data) => data.index == index,
1891 pub fn is_slice(self) -> bool {
1892 matches!(self.kind(), Slice(_))
1896 pub fn is_array_slice(self) -> bool {
1899 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1905 pub fn is_array(self) -> bool {
1906 matches!(self.kind(), Array(..))
1910 pub fn is_simd(self) -> bool {
1912 Adt(def, _) => def.repr().simd(),
1917 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1919 Array(ty, _) | Slice(ty) => *ty,
1920 Str => tcx.types.u8,
1921 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1925 pub fn expect_opaque_type(self) -> ty::OpaqueTypeKey<'tcx> {
1926 match *self.kind() {
1927 Opaque(def_id, substs) => ty::OpaqueTypeKey { def_id, substs },
1928 _ => bug!("`expect_opaque_type` called on non-opaque type: {}", self),
1932 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1934 Adt(def, substs) => {
1935 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1936 let variant = def.non_enum_variant();
1937 let f0_ty = variant.fields[0].ty(tcx, substs);
1939 match f0_ty.kind() {
1940 // If the first field is an array, we assume it is the only field and its
1941 // elements are the SIMD components.
1942 Array(f0_elem_ty, f0_len) => {
1943 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1944 // The way we evaluate the `N` in `[T; N]` here only works since we use
1945 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1946 // if we use it in generic code. See the `simd-array-trait` ui test.
1947 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1949 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1950 // all have the same type).
1951 _ => (variant.fields.len() as u64, f0_ty),
1954 _ => bug!("`simd_size_and_type` called on invalid type"),
1959 pub fn is_region_ptr(self) -> bool {
1960 matches!(self.kind(), Ref(..))
1964 pub fn is_mutable_ptr(self) -> bool {
1967 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1968 | Ref(_, _, hir::Mutability::Mut)
1972 /// Get the mutability of the reference or `None` when not a reference
1974 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1976 Ref(_, _, mutability) => Some(*mutability),
1982 pub fn is_unsafe_ptr(self) -> bool {
1983 matches!(self.kind(), RawPtr(_))
1986 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1988 pub fn is_any_ptr(self) -> bool {
1989 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1993 pub fn is_box(self) -> bool {
1995 Adt(def, _) => def.is_box(),
2000 /// Panics if called on any type other than `Box<T>`.
2001 pub fn boxed_ty(self) -> Ty<'tcx> {
2003 Adt(def, substs) if def.is_box() => substs.type_at(0),
2004 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
2008 /// A scalar type is one that denotes an atomic datum, with no sub-components.
2009 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
2010 /// contents are abstract to rustc.)
2012 pub fn is_scalar(self) -> bool {
2022 | Infer(IntVar(_) | FloatVar(_))
2026 /// Returns `true` if this type is a floating point type.
2028 pub fn is_floating_point(self) -> bool {
2029 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
2033 pub fn is_trait(self) -> bool {
2034 matches!(self.kind(), Dynamic(..))
2038 pub fn is_enum(self) -> bool {
2039 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
2043 pub fn is_union(self) -> bool {
2044 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
2048 pub fn is_closure(self) -> bool {
2049 matches!(self.kind(), Closure(..))
2053 pub fn is_generator(self) -> bool {
2054 matches!(self.kind(), Generator(..))
2058 pub fn is_integral(self) -> bool {
2059 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
2063 pub fn is_fresh_ty(self) -> bool {
2064 matches!(self.kind(), Infer(FreshTy(_)))
2068 pub fn is_fresh(self) -> bool {
2069 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
2073 pub fn is_char(self) -> bool {
2074 matches!(self.kind(), Char)
2078 pub fn is_numeric(self) -> bool {
2079 self.is_integral() || self.is_floating_point()
2083 pub fn is_signed(self) -> bool {
2084 matches!(self.kind(), Int(_))
2088 pub fn is_ptr_sized_integral(self) -> bool {
2089 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
2093 pub fn has_concrete_skeleton(self) -> bool {
2094 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
2097 /// Checks whether a type recursively contains another type
2099 /// Example: `Option<()>` contains `()`
2100 pub fn contains(self, other: Ty<'tcx>) -> bool {
2101 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
2103 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
2106 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
2107 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
2111 let cf = self.visit_with(&mut ContainsTyVisitor(other));
2115 /// Returns the type and mutability of `*ty`.
2117 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2118 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2119 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2121 Adt(def, _) if def.is_box() => {
2122 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
2124 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
2125 RawPtr(mt) if explicit => Some(*mt),
2130 /// Returns the type of `ty[i]`.
2131 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
2133 Array(ty, _) | Slice(ty) => Some(*ty),
2138 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2140 FnDef(def_id, substs) => tcx.fn_sig(*def_id).subst(tcx, substs),
2143 // ignore errors (#54954)
2144 ty::Binder::dummy(FnSig::fake())
2146 Closure(..) => bug!(
2147 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
2149 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
2154 pub fn is_fn(self) -> bool {
2155 matches!(self.kind(), FnDef(..) | FnPtr(_))
2159 pub fn is_fn_ptr(self) -> bool {
2160 matches!(self.kind(), FnPtr(_))
2164 pub fn is_impl_trait(self) -> bool {
2165 matches!(self.kind(), Opaque(..))
2169 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
2171 Adt(adt, _) => Some(*adt),
2176 /// Iterates over tuple fields.
2177 /// Panics when called on anything but a tuple.
2179 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
2181 Tuple(substs) => substs,
2182 _ => bug!("tuple_fields called on non-tuple"),
2186 /// If the type contains variants, returns the valid range of variant indices.
2188 // FIXME: This requires the optimized MIR in the case of generators.
2190 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2192 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2193 TyKind::Generator(def_id, substs, _) => {
2194 Some(substs.as_generator().variant_range(*def_id, tcx))
2200 /// If the type contains variants, returns the variant for `variant_index`.
2201 /// Panics if `variant_index` is out of range.
2203 // FIXME: This requires the optimized MIR in the case of generators.
2205 pub fn discriminant_for_variant(
2208 variant_index: VariantIdx,
2209 ) -> Option<Discr<'tcx>> {
2211 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2212 // This can actually happen during CTFE, see
2213 // https://github.com/rust-lang/rust/issues/89765.
2216 TyKind::Adt(adt, _) if adt.is_enum() => {
2217 Some(adt.discriminant_for_variant(tcx, variant_index))
2219 TyKind::Generator(def_id, substs, _) => {
2220 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2226 /// Returns the type of the discriminant of this type.
2227 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2229 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2230 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2232 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2233 let assoc_items = tcx.associated_item_def_ids(
2234 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2236 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2255 | ty::GeneratorWitness(..)
2259 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2262 | ty::Placeholder(_)
2263 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2264 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2269 /// Returns the type of metadata for (potentially fat) pointers to this type,
2270 /// and a boolean signifying if this is conditional on this type being `Sized`.
2271 pub fn ptr_metadata_ty(
2274 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2275 ) -> (Ty<'tcx>, bool) {
2276 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2279 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2290 | ty::GeneratorWitness(..)
2295 // Extern types have metadata = ().
2297 // If returned by `struct_tail_without_normalization` this is a unit struct
2298 // without any fields, or not a struct, and therefore is Sized.
2300 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2301 // a.k.a. unit type, which is Sized
2302 | ty::Tuple(..) => (tcx.types.unit, false),
2304 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2305 ty::Dynamic(..) => {
2306 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2307 (tcx.type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2310 // type parameters only have unit metadata if they're sized, so return true
2311 // to make sure we double check this during confirmation
2312 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2314 ty::Infer(ty::TyVar(_))
2316 | ty::Placeholder(..)
2317 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2318 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2323 /// When we create a closure, we record its kind (i.e., what trait
2324 /// it implements) into its `ClosureSubsts` using a type
2325 /// parameter. This is kind of a phantom type, except that the
2326 /// most convenient thing for us to are the integral types. This
2327 /// function converts such a special type into the closure
2328 /// kind. To go the other way, use
2329 /// `tcx.closure_kind_ty(closure_kind)`.
2331 /// Note that during type checking, we use an inference variable
2332 /// to represent the closure kind, because it has not yet been
2333 /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
2334 /// is complete, that type variable will be unified.
2335 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2337 Int(int_ty) => match int_ty {
2338 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2339 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2340 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2341 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2344 // "Bound" types appear in canonical queries when the
2345 // closure type is not yet known
2346 Bound(..) | Infer(_) => None,
2348 Error(_) => Some(ty::ClosureKind::Fn),
2350 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2354 /// Fast path helper for testing if a type is `Sized`.
2356 /// Returning true means the type is known to be sized. Returning
2357 /// `false` means nothing -- could be sized, might not be.
2359 /// Note that we could never rely on the fact that a type such as `[_]` is
2360 /// trivially `!Sized` because we could be in a type environment with a
2361 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2362 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2363 /// this method doesn't return `Option<bool>`.
2364 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2366 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2377 | ty::GeneratorWitness(..)
2381 | ty::Error(_) => true,
2383 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2385 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2387 ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(),
2389 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2391 ty::Infer(ty::TyVar(_)) => false,
2394 | ty::Placeholder(..)
2395 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2396 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2401 /// Fast path helper for primitives which are always `Copy` and which
2402 /// have a side-effect-free `Clone` impl.
2404 /// Returning true means the type is known to be pure and `Copy+Clone`.
2405 /// Returning `false` means nothing -- could be `Copy`, might not be.
2407 /// This is mostly useful for optimizations, as there are the types
2408 /// on which we can replace cloning with dereferencing.
2409 pub fn is_trivially_pure_clone_copy(self) -> bool {
2411 ty::Bool | ty::Char | ty::Never => true,
2413 // These aren't even `Clone`
2414 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2416 ty::Int(..) | ty::Uint(..) | ty::Float(..) => true,
2418 // The voldemort ZSTs are fine.
2419 ty::FnDef(..) => true,
2421 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2423 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2424 ty::Tuple(field_tys) => {
2425 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2428 // Sometimes traits aren't implemented for every ABI or arity,
2429 // because we can't be generic over everything yet.
2430 ty::FnPtr(..) => false,
2432 // Definitely absolutely not copy.
2433 ty::Ref(_, _, hir::Mutability::Mut) => false,
2435 // Thin pointers & thin shared references are pure-clone-copy, but for
2436 // anything with custom metadata it might be more complicated.
2437 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2439 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2441 // Might be, but not "trivial" so just giving the safe answer.
2442 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2444 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2446 ty::Bound(..) | ty::Placeholder(..) => {
2447 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2453 /// Extra information about why we ended up with a particular variance.
2454 /// This is only used to add more information to error messages, and
2455 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2456 /// may lead to confusing notes in error messages, it will never cause
2457 /// a miscompilation or unsoundness.
2459 /// When in doubt, use `VarianceDiagInfo::default()`
2460 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2461 pub enum VarianceDiagInfo<'tcx> {
2462 /// No additional information - this is the default.
2463 /// We will not add any additional information to error messages.
2466 /// We switched our variance because a generic argument occurs inside
2467 /// the invariant generic argument of another type.
2469 /// The generic type containing the generic parameter
2470 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2472 /// The index of the generic parameter being used
2473 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2478 impl<'tcx> VarianceDiagInfo<'tcx> {
2479 /// Mirrors `Variance::xform` - used to 'combine' the existing
2480 /// and new `VarianceDiagInfo`s when our variance changes.
2481 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2482 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2484 VarianceDiagInfo::None => other,
2485 VarianceDiagInfo::Invariant { .. } => self,