1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
7 use crate::infer::canonical::Canonical;
8 use crate::ty::fold::ValidateBoundVars;
9 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
10 use crate::ty::InferTy::{self, *};
11 use crate::ty::{self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeFoldable};
12 use crate::ty::{DelaySpanBugEmitted, List, ParamEnv, TyS};
13 use polonius_engine::Atom;
14 use rustc_data_structures::captures::Captures;
16 use rustc_hir::def_id::DefId;
17 use rustc_index::vec::Idx;
18 use rustc_macros::HashStable;
19 use rustc_span::symbol::{kw, Symbol};
20 use rustc_target::abi::VariantIdx;
21 use rustc_target::spec::abi;
23 use std::cmp::Ordering;
24 use std::marker::PhantomData;
26 use ty::util::IntTypeExt;
28 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
29 #[derive(HashStable, TypeFoldable, Lift)]
30 pub struct TypeAndMut<'tcx> {
32 pub mutbl: hir::Mutability,
35 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
37 /// A "free" region `fr` can be interpreted as "some region
38 /// at least as big as the scope `fr.scope`".
39 pub struct FreeRegion {
41 pub bound_region: BoundRegionKind,
44 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
46 pub enum BoundRegionKind {
47 /// An anonymous region parameter for a given fn (&T)
50 /// Named region parameters for functions (a in &'a T)
52 /// The `DefId` is needed to distinguish free regions in
53 /// the event of shadowing.
54 BrNamed(DefId, Symbol),
56 /// Anonymous region for the implicit env pointer parameter
61 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
63 pub struct BoundRegion {
65 pub kind: BoundRegionKind,
68 impl BoundRegionKind {
69 pub fn is_named(&self) -> bool {
71 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
77 /// Defines the kinds of types used by the type system.
79 /// Types written by the user start out as [hir::TyKind](rustc_hir::TyKind) and get
80 /// converted to this representation using `AstConv::ast_ty_to_ty`.
81 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)]
83 #[rustc_diagnostic_item = "TyKind"]
84 pub enum TyKind<'tcx> {
85 /// The primitive boolean type. Written as `bool`.
88 /// The primitive character type; holds a Unicode scalar value
89 /// (a non-surrogate code point). Written as `char`.
92 /// A primitive signed integer type. For example, `i32`.
95 /// A primitive unsigned integer type. For example, `u32`.
98 /// A primitive floating-point type. For example, `f64`.
101 /// Algebraic data types (ADT). For example: structures, enumerations and unions.
103 /// For example, the type `List<i32>` would be represented using the `AdtDef`
104 /// for `struct List<T>` and the substs `[i32]`.
106 /// Note that generic parameters in fields only get lazily substituted
107 /// by using something like `adt_def.all_fields().map(|field| field.ty(tcx, substs))`.
108 Adt(&'tcx AdtDef, SubstsRef<'tcx>),
110 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
113 /// The pointee of a string slice. Written as `str`.
116 /// An array with the given length. Written as `[T; N]`.
117 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
119 /// The pointee of an array slice. Written as `[T]`.
122 /// A raw pointer. Written as `*mut T` or `*const T`
123 RawPtr(TypeAndMut<'tcx>),
125 /// A reference; a pointer with an associated lifetime. Written as
126 /// `&'a mut T` or `&'a T`.
127 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
129 /// The anonymous type of a function declaration/definition. Each
130 /// function has a unique type.
132 /// For the function `fn foo() -> i32 { 3 }` this type would be
133 /// shown to the user as `fn() -> i32 {foo}`.
135 /// For example the type of `bar` here:
137 /// fn foo() -> i32 { 1 }
138 /// let bar = foo; // bar: fn() -> i32 {foo}
140 FnDef(DefId, SubstsRef<'tcx>),
142 /// A pointer to a function. Written as `fn() -> i32`.
144 /// Note that both functions and closures start out as either
145 /// [FnDef] or [Closure] which can be then be coerced to this variant.
147 /// For example the type of `bar` here:
150 /// fn foo() -> i32 { 1 }
151 /// let bar: fn() -> i32 = foo;
153 FnPtr(PolyFnSig<'tcx>),
155 /// A trait object. Written as `dyn for<'b> Trait<'b, Assoc = u32> + Send + 'a`.
156 Dynamic(&'tcx List<Binder<'tcx, ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
158 /// The anonymous type of a closure. Used to represent the type of `|a| a`.
160 /// Closure substs contain both the - potentially substituted - generic parameters
161 /// of its parent and some synthetic parameters. See the documentation for
162 /// [ClosureSubsts] for more details.
163 Closure(DefId, SubstsRef<'tcx>),
165 /// The anonymous type of a generator. Used to represent the type of
168 /// For more info about generator substs, visit the documentation for
169 /// [GeneratorSubsts].
170 Generator(DefId, SubstsRef<'tcx>, hir::Movability),
172 /// A type representing the types stored inside a generator.
173 /// This should only appear as part of the [GeneratorSubsts].
175 /// Note that the captured variables for generators are stored separately
176 /// using a tuple in the same way as for closures.
178 /// Unlike upvars, the witness can reference lifetimes from
179 /// inside of the generator itself. To deal with them in
180 /// the type of the generator, we convert them to higher ranked
181 /// lifetimes bound by the witness itself.
183 /// Looking at the following example, the witness for this generator
184 /// may end up as something like `for<'a> [Vec<i32>, &'a Vec<i32>]`:
188 /// let x = &vec![3];
193 GeneratorWitness(Binder<'tcx, &'tcx List<Ty<'tcx>>>),
195 /// The never type `!`.
198 /// A tuple type. For example, `(i32, bool)`.
199 /// Use `TyS::tuple_fields` to iterate over the field types.
200 Tuple(SubstsRef<'tcx>),
202 /// The projection of an associated type. For example,
203 /// `<T as Trait<..>>::N`.
204 Projection(ProjectionTy<'tcx>),
206 /// Opaque (`impl Trait`) type found in a return type.
208 /// The `DefId` comes either from
209 /// * the `impl Trait` ast::Ty node,
210 /// * or the `type Foo = impl Trait` declaration
212 /// For RTIT the substitutions are for the generics of the function,
213 /// while for TAIT it is used for the generic parameters of the alias.
214 Opaque(DefId, SubstsRef<'tcx>),
216 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}`.
219 /// Bound type variable, used to represent the `'a` in `for<'a> fn(&'a ())`.
221 /// For canonical queries, we replace inference variables with bound variables,
222 /// so e.g. when checking whether `&'_ (): Trait<_>` holds, we canonicalize that to
223 /// `for<'a, T> &'a (): Trait<T>` and then convert the introduced bound variables
224 /// back to inference variables in a new inference context when inside of the query.
226 /// See the `rustc-dev-guide` for more details about
227 /// [higher-ranked trait bounds][1] and [canonical queries][2].
229 /// [1]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
230 /// [2]: https://rustc-dev-guide.rust-lang.org/traits/canonical-queries.html
231 Bound(ty::DebruijnIndex, BoundTy),
233 /// A placeholder type, used during higher ranked subtyping to instantiate
235 Placeholder(ty::PlaceholderType),
237 /// A type variable used during type checking.
239 /// Similar to placeholders, inference variables also live in a universe to
240 /// correctly deal with higher ranked types. Though unlike placeholders,
241 /// that universe is stored in the `InferCtxt` instead of directly
242 /// inside of the type.
245 /// A placeholder for a type which could not be computed; this is
246 /// propagated to avoid useless error messages.
247 Error(DelaySpanBugEmitted),
250 impl<'tcx> TyKind<'tcx> {
252 pub fn is_primitive(&self) -> bool {
253 matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_))
256 /// Get the article ("a" or "an") to use with this type.
257 pub fn article(&self) -> &'static str {
259 Int(_) | Float(_) | Array(_, _) => "an",
260 Adt(def, _) if def.is_enum() => "an",
261 // This should never happen, but ICEing and causing the user's code
262 // to not compile felt too harsh.
269 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
270 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
271 static_assert_size!(TyKind<'_>, 32);
273 /// A closure can be modeled as a struct that looks like:
275 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
279 /// - 'l0...'li and T0...Tj are the generic parameters
280 /// in scope on the function that defined the closure,
281 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
282 /// is rather hackily encoded via a scalar type. See
283 /// `TyS::to_opt_closure_kind` for details.
284 /// - CS represents the *closure signature*, representing as a `fn()`
285 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
286 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
288 /// - U is a type parameter representing the types of its upvars, tupled up
289 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
290 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
292 /// So, for example, given this function:
294 /// fn foo<'a, T>(data: &'a mut T) {
295 /// do(|| data.count += 1)
298 /// the type of the closure would be something like:
300 /// struct Closure<'a, T, U>(...U);
302 /// Note that the type of the upvar is not specified in the struct.
303 /// You may wonder how the impl would then be able to use the upvar,
304 /// if it doesn't know it's type? The answer is that the impl is
305 /// (conceptually) not fully generic over Closure but rather tied to
306 /// instances with the expected upvar types:
308 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
312 /// You can see that the *impl* fully specified the type of the upvar
313 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
314 /// (Here, I am assuming that `data` is mut-borrowed.)
316 /// Now, the last question you may ask is: Why include the upvar types
317 /// in an extra type parameter? The reason for this design is that the
318 /// upvar types can reference lifetimes that are internal to the
319 /// creating function. In my example above, for example, the lifetime
320 /// `'b` represents the scope of the closure itself; this is some
321 /// subset of `foo`, probably just the scope of the call to the to
322 /// `do()`. If we just had the lifetime/type parameters from the
323 /// enclosing function, we couldn't name this lifetime `'b`. Note that
324 /// there can also be lifetimes in the types of the upvars themselves,
325 /// if one of them happens to be a reference to something that the
326 /// creating fn owns.
328 /// OK, you say, so why not create a more minimal set of parameters
329 /// that just includes the extra lifetime parameters? The answer is
330 /// primarily that it would be hard --- we don't know at the time when
331 /// we create the closure type what the full types of the upvars are,
332 /// nor do we know which are borrowed and which are not. In this
333 /// design, we can just supply a fresh type parameter and figure that
336 /// All right, you say, but why include the type parameters from the
337 /// original function then? The answer is that codegen may need them
338 /// when monomorphizing, and they may not appear in the upvars. A
339 /// closure could capture no variables but still make use of some
340 /// in-scope type parameter with a bound (e.g., if our example above
341 /// had an extra `U: Default`, and the closure called `U::default()`).
343 /// There is another reason. This design (implicitly) prohibits
344 /// closures from capturing themselves (except via a trait
345 /// object). This simplifies closure inference considerably, since it
346 /// means that when we infer the kind of a closure or its upvars, we
347 /// don't have to handle cycles where the decisions we make for
348 /// closure C wind up influencing the decisions we ought to make for
349 /// closure C (which would then require fixed point iteration to
350 /// handle). Plus it fixes an ICE. :P
354 /// Generators are handled similarly in `GeneratorSubsts`. The set of
355 /// type parameters is similar, but `CK` and `CS` are replaced by the
356 /// following type parameters:
358 /// * `GS`: The generator's "resume type", which is the type of the
359 /// argument passed to `resume`, and the type of `yield` expressions
360 /// inside the generator.
361 /// * `GY`: The "yield type", which is the type of values passed to
362 /// `yield` inside the generator.
363 /// * `GR`: The "return type", which is the type of value returned upon
364 /// completion of the generator.
365 /// * `GW`: The "generator witness".
366 #[derive(Copy, Clone, Debug, TypeFoldable)]
367 pub struct ClosureSubsts<'tcx> {
368 /// Lifetime and type parameters from the enclosing function,
369 /// concatenated with a tuple containing the types of the upvars.
371 /// These are separated out because codegen wants to pass them around
372 /// when monomorphizing.
373 pub substs: SubstsRef<'tcx>,
376 /// Struct returned by `split()`.
377 pub struct ClosureSubstsParts<'tcx, T> {
378 pub parent_substs: &'tcx [GenericArg<'tcx>],
379 pub closure_kind_ty: T,
380 pub closure_sig_as_fn_ptr_ty: T,
381 pub tupled_upvars_ty: T,
384 impl<'tcx> ClosureSubsts<'tcx> {
385 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
386 /// for the closure parent, alongside additional closure-specific components.
389 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
390 ) -> ClosureSubsts<'tcx> {
392 substs: tcx.mk_substs(
393 parts.parent_substs.iter().copied().chain(
394 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
396 .map(|&ty| ty.into()),
402 /// Divides the closure substs into their respective components.
403 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
404 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
405 match self.substs[..] {
407 ref parent_substs @ ..,
409 closure_sig_as_fn_ptr_ty,
411 ] => ClosureSubstsParts {
414 closure_sig_as_fn_ptr_ty,
417 _ => bug!("closure substs missing synthetics"),
421 /// Returns `true` only if enough of the synthetic types are known to
422 /// allow using all of the methods on `ClosureSubsts` without panicking.
424 /// Used primarily by `ty::print::pretty` to be able to handle closure
425 /// types that haven't had their synthetic types substituted in.
426 pub fn is_valid(self) -> bool {
427 self.substs.len() >= 3
428 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
431 /// Returns the substitutions of the closure's parent.
432 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
433 self.split().parent_substs
436 /// Returns an iterator over the list of types of captured paths by the closure.
437 /// In case there was a type error in figuring out the types of the captured path, an
438 /// empty iterator is returned.
440 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
441 match self.tupled_upvars_ty().kind() {
442 TyKind::Error(_) => None,
443 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
444 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
445 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
451 /// Returns the tuple type representing the upvars for this closure.
453 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
454 self.split().tupled_upvars_ty.expect_ty()
457 /// Returns the closure kind for this closure; may return a type
458 /// variable during inference. To get the closure kind during
459 /// inference, use `infcx.closure_kind(substs)`.
460 pub fn kind_ty(self) -> Ty<'tcx> {
461 self.split().closure_kind_ty.expect_ty()
464 /// Returns the `fn` pointer type representing the closure signature for this
466 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
467 // type is known at the time of the creation of `ClosureSubsts`,
468 // see `rustc_typeck::check::closure`.
469 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
470 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
473 /// Returns the closure kind for this closure; only usable outside
474 /// of an inference context, because in that context we know that
475 /// there are no type variables.
477 /// If you have an inference context, use `infcx.closure_kind()`.
478 pub fn kind(self) -> ty::ClosureKind {
479 self.kind_ty().to_opt_closure_kind().unwrap()
482 /// Extracts the signature from the closure.
483 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
484 let ty = self.sig_as_fn_ptr_ty();
486 ty::FnPtr(sig) => *sig,
487 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
492 /// Similar to `ClosureSubsts`; see the above documentation for more.
493 #[derive(Copy, Clone, Debug, TypeFoldable)]
494 pub struct GeneratorSubsts<'tcx> {
495 pub substs: SubstsRef<'tcx>,
498 pub struct GeneratorSubstsParts<'tcx, T> {
499 pub parent_substs: &'tcx [GenericArg<'tcx>],
504 pub tupled_upvars_ty: T,
507 impl<'tcx> GeneratorSubsts<'tcx> {
508 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
509 /// for the generator parent, alongside additional generator-specific components.
512 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
513 ) -> GeneratorSubsts<'tcx> {
515 substs: tcx.mk_substs(
516 parts.parent_substs.iter().copied().chain(
522 parts.tupled_upvars_ty,
525 .map(|&ty| ty.into()),
531 /// Divides the generator substs into their respective components.
532 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
533 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
534 match self.substs[..] {
535 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
536 GeneratorSubstsParts {
545 _ => bug!("generator substs missing synthetics"),
549 /// Returns `true` only if enough of the synthetic types are known to
550 /// allow using all of the methods on `GeneratorSubsts` without panicking.
552 /// Used primarily by `ty::print::pretty` to be able to handle generator
553 /// types that haven't had their synthetic types substituted in.
554 pub fn is_valid(self) -> bool {
555 self.substs.len() >= 5
556 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
559 /// Returns the substitutions of the generator's parent.
560 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
561 self.split().parent_substs
564 /// This describes the types that can be contained in a generator.
565 /// It will be a type variable initially and unified in the last stages of typeck of a body.
566 /// It contains a tuple of all the types that could end up on a generator frame.
567 /// The state transformation MIR pass may only produce layouts which mention types
568 /// in this tuple. Upvars are not counted here.
569 pub fn witness(self) -> Ty<'tcx> {
570 self.split().witness.expect_ty()
573 /// Returns an iterator over the list of types of captured paths by the generator.
574 /// In case there was a type error in figuring out the types of the captured path, an
575 /// empty iterator is returned.
577 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
578 match self.tupled_upvars_ty().kind() {
579 TyKind::Error(_) => None,
580 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
581 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
582 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
588 /// Returns the tuple type representing the upvars for this generator.
590 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
591 self.split().tupled_upvars_ty.expect_ty()
594 /// Returns the type representing the resume type of the generator.
595 pub fn resume_ty(self) -> Ty<'tcx> {
596 self.split().resume_ty.expect_ty()
599 /// Returns the type representing the yield type of the generator.
600 pub fn yield_ty(self) -> Ty<'tcx> {
601 self.split().yield_ty.expect_ty()
604 /// Returns the type representing the return type of the generator.
605 pub fn return_ty(self) -> Ty<'tcx> {
606 self.split().return_ty.expect_ty()
609 /// Returns the "generator signature", which consists of its yield
610 /// and return types.
612 /// N.B., some bits of the code prefers to see this wrapped in a
613 /// binder, but it never contains bound regions. Probably this
614 /// function should be removed.
615 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
616 ty::Binder::dummy(self.sig())
619 /// Returns the "generator signature", which consists of its resume, yield
620 /// and return types.
621 pub fn sig(self) -> GenSig<'tcx> {
623 resume_ty: self.resume_ty(),
624 yield_ty: self.yield_ty(),
625 return_ty: self.return_ty(),
630 impl<'tcx> GeneratorSubsts<'tcx> {
631 /// Generator has not been resumed yet.
632 pub const UNRESUMED: usize = 0;
633 /// Generator has returned or is completed.
634 pub const RETURNED: usize = 1;
635 /// Generator has been poisoned.
636 pub const POISONED: usize = 2;
638 const UNRESUMED_NAME: &'static str = "Unresumed";
639 const RETURNED_NAME: &'static str = "Returned";
640 const POISONED_NAME: &'static str = "Panicked";
642 /// The valid variant indices of this generator.
644 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
645 // FIXME requires optimized MIR
646 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
647 VariantIdx::new(0)..VariantIdx::new(num_variants)
650 /// The discriminant for the given variant. Panics if the `variant_index` is
653 pub fn discriminant_for_variant(
657 variant_index: VariantIdx,
659 // Generators don't support explicit discriminant values, so they are
660 // the same as the variant index.
661 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
662 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
665 /// The set of all discriminants for the generator, enumerated with their
668 pub fn discriminants(
672 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
673 self.variant_range(def_id, tcx).map(move |index| {
674 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
678 /// Calls `f` with a reference to the name of the enumerator for the given
680 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
682 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
683 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
684 Self::POISONED => Cow::from(Self::POISONED_NAME),
685 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
689 /// The type of the state discriminant used in the generator type.
691 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
695 /// This returns the types of the MIR locals which had to be stored across suspension points.
696 /// It is calculated in rustc_const_eval::transform::generator::StateTransform.
697 /// All the types here must be in the tuple in GeneratorInterior.
699 /// The locals are grouped by their variant number. Note that some locals may
700 /// be repeated in multiple variants.
706 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
707 let layout = tcx.generator_layout(def_id).unwrap();
708 layout.variant_fields.iter().map(move |variant| {
709 variant.iter().map(move |field| layout.field_tys[*field].subst(tcx, self.substs))
713 /// This is the types of the fields of a generator which are not stored in a
716 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
721 #[derive(Debug, Copy, Clone, HashStable)]
722 pub enum UpvarSubsts<'tcx> {
723 Closure(SubstsRef<'tcx>),
724 Generator(SubstsRef<'tcx>),
727 impl<'tcx> UpvarSubsts<'tcx> {
728 /// Returns an iterator over the list of types of captured paths by the closure/generator.
729 /// In case there was a type error in figuring out the types of the captured path, an
730 /// empty iterator is returned.
732 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
733 let tupled_tys = match self {
734 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
735 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
738 match tupled_tys.kind() {
739 TyKind::Error(_) => None,
740 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
741 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
742 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
749 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
751 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
752 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
757 /// An inline const is modeled like
759 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
763 /// - 'l0...'li and T0...Tj are the generic parameters
764 /// inherited from the item that defined the inline const,
765 /// - R represents the type of the constant.
767 /// When the inline const is instantiated, `R` is substituted as the actual inferred
768 /// type of the constant. The reason that `R` is represented as an extra type parameter
769 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
770 /// inline const can reference lifetimes that are internal to the creating function.
771 #[derive(Copy, Clone, Debug, TypeFoldable)]
772 pub struct InlineConstSubsts<'tcx> {
773 /// Generic parameters from the enclosing item,
774 /// concatenated with the inferred type of the constant.
775 pub substs: SubstsRef<'tcx>,
778 /// Struct returned by `split()`.
779 pub struct InlineConstSubstsParts<'tcx, T> {
780 pub parent_substs: &'tcx [GenericArg<'tcx>],
784 impl<'tcx> InlineConstSubsts<'tcx> {
785 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
788 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
789 ) -> InlineConstSubsts<'tcx> {
791 substs: tcx.mk_substs(
792 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
797 /// Divides the inline const substs into their respective components.
798 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
799 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
800 match self.substs[..] {
801 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
802 _ => bug!("inline const substs missing synthetics"),
806 /// Returns the substitutions of the inline const's parent.
807 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
808 self.split().parent_substs
811 /// Returns the type of this inline const.
812 pub fn ty(self) -> Ty<'tcx> {
813 self.split().ty.expect_ty()
817 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
818 #[derive(HashStable, TypeFoldable)]
819 pub enum ExistentialPredicate<'tcx> {
820 /// E.g., `Iterator`.
821 Trait(ExistentialTraitRef<'tcx>),
822 /// E.g., `Iterator::Item = T`.
823 Projection(ExistentialProjection<'tcx>),
828 impl<'tcx> ExistentialPredicate<'tcx> {
829 /// Compares via an ordering that will not change if modules are reordered or other changes are
830 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
831 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
832 use self::ExistentialPredicate::*;
833 match (*self, *other) {
834 (Trait(_), Trait(_)) => Ordering::Equal,
835 (Projection(ref a), Projection(ref b)) => {
836 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
838 (AutoTrait(ref a), AutoTrait(ref b)) => {
839 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
841 (Trait(_), _) => Ordering::Less,
842 (Projection(_), Trait(_)) => Ordering::Greater,
843 (Projection(_), _) => Ordering::Less,
844 (AutoTrait(_), _) => Ordering::Greater,
849 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
850 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
851 use crate::ty::ToPredicate;
852 match self.skip_binder() {
853 ExistentialPredicate::Trait(tr) => {
854 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
856 ExistentialPredicate::Projection(p) => {
857 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
859 ExistentialPredicate::AutoTrait(did) => {
860 let trait_ref = self.rebind(ty::TraitRef {
862 substs: tcx.mk_substs_trait(self_ty, &[]),
864 trait_ref.without_const().to_predicate(tcx)
870 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
871 /// Returns the "principal `DefId`" of this set of existential predicates.
873 /// A Rust trait object type consists (in addition to a lifetime bound)
874 /// of a set of trait bounds, which are separated into any number
875 /// of auto-trait bounds, and at most one non-auto-trait bound. The
876 /// non-auto-trait bound is called the "principal" of the trait
879 /// Only the principal can have methods or type parameters (because
880 /// auto traits can have neither of them). This is important, because
881 /// it means the auto traits can be treated as an unordered set (methods
882 /// would force an order for the vtable, while relating traits with
883 /// type parameters without knowing the order to relate them in is
884 /// a rather non-trivial task).
886 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
887 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
888 /// are the set `{Sync}`.
890 /// It is also possible to have a "trivial" trait object that
891 /// consists only of auto traits, with no principal - for example,
892 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
893 /// is `{Send, Sync}`, while there is no principal. These trait objects
894 /// have a "trivial" vtable consisting of just the size, alignment,
896 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
898 .map_bound(|this| match this {
899 ExistentialPredicate::Trait(tr) => Some(tr),
905 pub fn principal_def_id(&self) -> Option<DefId> {
906 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
910 pub fn projection_bounds<'a>(
912 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
913 self.iter().filter_map(|predicate| {
915 .map_bound(|pred| match pred {
916 ExistentialPredicate::Projection(projection) => Some(projection),
924 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
925 self.iter().filter_map(|predicate| match predicate.skip_binder() {
926 ExistentialPredicate::AutoTrait(did) => Some(did),
932 /// A complete reference to a trait. These take numerous guises in syntax,
933 /// but perhaps the most recognizable form is in a where-clause:
937 /// This would be represented by a trait-reference where the `DefId` is the
938 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
939 /// and `U` as parameter 1.
941 /// Trait references also appear in object types like `Foo<U>`, but in
942 /// that case the `Self` parameter is absent from the substitutions.
943 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
944 #[derive(HashStable, TypeFoldable)]
945 pub struct TraitRef<'tcx> {
947 pub substs: SubstsRef<'tcx>,
950 impl<'tcx> TraitRef<'tcx> {
951 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
952 TraitRef { def_id, substs }
955 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
956 /// are the parameters defined on trait.
957 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
958 ty::Binder::dummy(TraitRef {
960 substs: InternalSubsts::identity_for_item(tcx, def_id),
965 pub fn self_ty(&self) -> Ty<'tcx> {
966 self.substs.type_at(0)
972 substs: SubstsRef<'tcx>,
973 ) -> ty::TraitRef<'tcx> {
974 let defs = tcx.generics_of(trait_id);
976 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
980 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
982 impl<'tcx> PolyTraitRef<'tcx> {
983 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
984 self.map_bound_ref(|tr| tr.self_ty())
987 pub fn def_id(&self) -> DefId {
988 self.skip_binder().def_id
991 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
992 self.map_bound(|trait_ref| ty::TraitPredicate {
994 constness: ty::BoundConstness::NotConst,
995 polarity: ty::ImplPolarity::Positive,
1000 /// An existential reference to a trait, where `Self` is erased.
1001 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
1003 /// exists T. T: Trait<'a, 'b, X, Y>
1005 /// The substitutions don't include the erased `Self`, only trait
1006 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
1007 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1008 #[derive(HashStable, TypeFoldable)]
1009 pub struct ExistentialTraitRef<'tcx> {
1011 pub substs: SubstsRef<'tcx>,
1014 impl<'tcx> ExistentialTraitRef<'tcx> {
1015 pub fn erase_self_ty(
1017 trait_ref: ty::TraitRef<'tcx>,
1018 ) -> ty::ExistentialTraitRef<'tcx> {
1019 // Assert there is a Self.
1020 trait_ref.substs.type_at(0);
1022 ty::ExistentialTraitRef {
1023 def_id: trait_ref.def_id,
1024 substs: tcx.intern_substs(&trait_ref.substs[1..]),
1028 /// Object types don't have a self type specified. Therefore, when
1029 /// we convert the principal trait-ref into a normal trait-ref,
1030 /// you must give *some* self type. A common choice is `mk_err()`
1031 /// or some placeholder type.
1032 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
1033 // otherwise the escaping vars would be captured by the binder
1034 // debug_assert!(!self_ty.has_escaping_bound_vars());
1036 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
1040 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
1042 impl<'tcx> PolyExistentialTraitRef<'tcx> {
1043 pub fn def_id(&self) -> DefId {
1044 self.skip_binder().def_id
1047 /// Object types don't have a self type specified. Therefore, when
1048 /// we convert the principal trait-ref into a normal trait-ref,
1049 /// you must give *some* self type. A common choice is `mk_err()`
1050 /// or some placeholder type.
1051 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
1052 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
1056 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1057 #[derive(HashStable)]
1058 pub enum BoundVariableKind {
1060 Region(BoundRegionKind),
1064 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
1065 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
1066 /// (which would be represented by the type `PolyTraitRef ==
1067 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
1068 /// erase, or otherwise "discharge" these bound vars, we change the
1069 /// type from `Binder<'tcx, T>` to just `T` (see
1070 /// e.g., `liberate_late_bound_regions`).
1072 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
1073 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1074 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
1076 impl<'tcx, T> Binder<'tcx, T>
1078 T: TypeFoldable<'tcx>,
1080 /// Wraps `value` in a binder, asserting that `value` does not
1081 /// contain any bound vars that would be bound by the
1082 /// binder. This is commonly used to 'inject' a value T into a
1083 /// different binding level.
1084 pub fn dummy(value: T) -> Binder<'tcx, T> {
1085 assert!(!value.has_escaping_bound_vars());
1086 Binder(value, ty::List::empty())
1089 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
1090 if cfg!(debug_assertions) {
1091 let mut validator = ValidateBoundVars::new(vars);
1092 value.visit_with(&mut validator);
1098 impl<'tcx, T> Binder<'tcx, T> {
1099 /// Skips the binder and returns the "bound" value. This is a
1100 /// risky thing to do because it's easy to get confused about
1101 /// De Bruijn indices and the like. It is usually better to
1102 /// discharge the binder using `no_bound_vars` or
1103 /// `replace_late_bound_regions` or something like
1104 /// that. `skip_binder` is only valid when you are either
1105 /// extracting data that has nothing to do with bound vars, you
1106 /// are doing some sort of test that does not involve bound
1107 /// regions, or you are being very careful about your depth
1110 /// Some examples where `skip_binder` is reasonable:
1112 /// - extracting the `DefId` from a PolyTraitRef;
1113 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1114 /// a type parameter `X`, since the type `X` does not reference any regions
1115 pub fn skip_binder(self) -> T {
1119 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1123 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1124 Binder(&self.0, self.1)
1127 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1131 let value = f(&self.0);
1132 Binder(value, self.1)
1135 pub fn map_bound_ref<F, U: TypeFoldable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1139 self.as_ref().map_bound(f)
1142 pub fn map_bound<F, U: TypeFoldable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1146 let value = f(self.0);
1147 if cfg!(debug_assertions) {
1148 let mut validator = ValidateBoundVars::new(self.1);
1149 value.visit_with(&mut validator);
1151 Binder(value, self.1)
1154 pub fn try_map_bound<F, U: TypeFoldable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1156 F: FnOnce(T) -> Result<U, E>,
1158 let value = f(self.0)?;
1159 if cfg!(debug_assertions) {
1160 let mut validator = ValidateBoundVars::new(self.1);
1161 value.visit_with(&mut validator);
1163 Ok(Binder(value, self.1))
1166 /// Wraps a `value` in a binder, using the same bound variables as the
1167 /// current `Binder`. This should not be used if the new value *changes*
1168 /// the bound variables. Note: the (old or new) value itself does not
1169 /// necessarily need to *name* all the bound variables.
1171 /// This currently doesn't do anything different than `bind`, because we
1172 /// don't actually track bound vars. However, semantically, it is different
1173 /// because bound vars aren't allowed to change here, whereas they are
1174 /// in `bind`. This may be (debug) asserted in the future.
1175 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1177 U: TypeFoldable<'tcx>,
1179 if cfg!(debug_assertions) {
1180 let mut validator = ValidateBoundVars::new(self.bound_vars());
1181 value.visit_with(&mut validator);
1183 Binder(value, self.1)
1186 /// Unwraps and returns the value within, but only if it contains
1187 /// no bound vars at all. (In other words, if this binder --
1188 /// and indeed any enclosing binder -- doesn't bind anything at
1189 /// all.) Otherwise, returns `None`.
1191 /// (One could imagine having a method that just unwraps a single
1192 /// binder, but permits late-bound vars bound by enclosing
1193 /// binders, but that would require adjusting the debruijn
1194 /// indices, and given the shallow binding structure we often use,
1195 /// would not be that useful.)
1196 pub fn no_bound_vars(self) -> Option<T>
1198 T: TypeFoldable<'tcx>,
1200 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1203 /// Splits the contents into two things that share the same binder
1204 /// level as the original, returning two distinct binders.
1206 /// `f` should consider bound regions at depth 1 to be free, and
1207 /// anything it produces with bound regions at depth 1 will be
1208 /// bound in the resulting return values.
1209 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1211 F: FnOnce(T) -> (U, V),
1213 let (u, v) = f(self.0);
1214 (Binder(u, self.1), Binder(v, self.1))
1218 impl<'tcx, T> Binder<'tcx, Option<T>> {
1219 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1220 let bound_vars = self.1;
1221 self.0.map(|v| Binder(v, bound_vars))
1225 /// Represents the projection of an associated type. In explicit UFCS
1226 /// form this would be written `<T as Trait<..>>::N`.
1227 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1228 #[derive(HashStable, TypeFoldable)]
1229 pub struct ProjectionTy<'tcx> {
1230 /// The parameters of the associated item.
1231 pub substs: SubstsRef<'tcx>,
1233 /// The `DefId` of the `TraitItem` for the associated type `N`.
1235 /// Note that this is not the `DefId` of the `TraitRef` containing this
1236 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
1237 pub item_def_id: DefId,
1240 impl<'tcx> ProjectionTy<'tcx> {
1241 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1242 tcx.associated_item(self.item_def_id).container.id()
1245 /// Extracts the underlying trait reference and own substs from this projection.
1246 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1247 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1248 pub fn trait_ref_and_own_substs(
1251 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1252 let def_id = tcx.associated_item(self.item_def_id).container.id();
1253 let trait_generics = tcx.generics_of(def_id);
1255 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1256 &self.substs[trait_generics.count()..],
1260 /// Extracts the underlying trait reference from this projection.
1261 /// For example, if this is a projection of `<T as Iterator>::Item`,
1262 /// then this function would return a `T: Iterator` trait reference.
1264 /// WARNING: This will drop the substs for generic associated types
1265 /// consider calling [Self::trait_ref_and_own_substs] to get those
1267 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1268 let def_id = self.trait_def_id(tcx);
1269 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1272 pub fn self_ty(&self) -> Ty<'tcx> {
1273 self.substs.type_at(0)
1277 #[derive(Copy, Clone, Debug, TypeFoldable)]
1278 pub struct GenSig<'tcx> {
1279 pub resume_ty: Ty<'tcx>,
1280 pub yield_ty: Ty<'tcx>,
1281 pub return_ty: Ty<'tcx>,
1284 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1286 /// Signature of a function type, which we have arbitrarily
1287 /// decided to use to refer to the input/output types.
1289 /// - `inputs`: is the list of arguments and their modes.
1290 /// - `output`: is the return type.
1291 /// - `c_variadic`: indicates whether this is a C-variadic function.
1292 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1293 #[derive(HashStable, TypeFoldable)]
1294 pub struct FnSig<'tcx> {
1295 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1296 pub c_variadic: bool,
1297 pub unsafety: hir::Unsafety,
1301 impl<'tcx> FnSig<'tcx> {
1302 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1303 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1306 pub fn output(&self) -> Ty<'tcx> {
1307 self.inputs_and_output[self.inputs_and_output.len() - 1]
1310 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1312 fn fake() -> FnSig<'tcx> {
1314 inputs_and_output: List::empty(),
1316 unsafety: hir::Unsafety::Normal,
1317 abi: abi::Abi::Rust,
1322 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1324 impl<'tcx> PolyFnSig<'tcx> {
1326 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1327 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1330 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1331 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1333 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1334 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1337 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1338 self.map_bound_ref(|fn_sig| fn_sig.output())
1340 pub fn c_variadic(&self) -> bool {
1341 self.skip_binder().c_variadic
1343 pub fn unsafety(&self) -> hir::Unsafety {
1344 self.skip_binder().unsafety
1346 pub fn abi(&self) -> abi::Abi {
1347 self.skip_binder().abi
1351 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1353 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1354 #[derive(HashStable)]
1355 pub struct ParamTy {
1360 impl<'tcx> ParamTy {
1361 pub fn new(index: u32, name: Symbol) -> ParamTy {
1362 ParamTy { index, name }
1365 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1366 ParamTy::new(def.index, def.name)
1370 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1371 tcx.mk_ty_param(self.index, self.name)
1375 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1376 #[derive(HashStable)]
1377 pub struct ParamConst {
1383 pub fn new(index: u32, name: Symbol) -> ParamConst {
1384 ParamConst { index, name }
1387 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1388 ParamConst::new(def.index, def.name)
1392 pub type Region<'tcx> = &'tcx RegionKind;
1394 /// Representation of regions. Note that the NLL checker uses a distinct
1395 /// representation of regions. For this reason, it internally replaces all the
1396 /// regions with inference variables -- the index of the variable is then used
1397 /// to index into internal NLL data structures. See `rustc_const_eval::borrow_check`
1398 /// module for more information.
1400 /// ## The Region lattice within a given function
1402 /// In general, the region lattice looks like
1405 /// static ----------+-----...------+ (greatest)
1407 /// early-bound and | |
1408 /// free regions | |
1411 /// empty(root) placeholder(U1) |
1413 /// | / placeholder(Un)
1418 /// empty(Un) -------- (smallest)
1421 /// Early-bound/free regions are the named lifetimes in scope from the
1422 /// function declaration. They have relationships to one another
1423 /// determined based on the declared relationships from the
1426 /// Note that inference variables and bound regions are not included
1427 /// in this diagram. In the case of inference variables, they should
1428 /// be inferred to some other region from the diagram. In the case of
1429 /// bound regions, they are excluded because they don't make sense to
1430 /// include -- the diagram indicates the relationship between free
1433 /// ## Inference variables
1435 /// During region inference, we sometimes create inference variables,
1436 /// represented as `ReVar`. These will be inferred by the code in
1437 /// `infer::lexical_region_resolve` to some free region from the
1438 /// lattice above (the minimal region that meets the
1441 /// During NLL checking, where regions are defined differently, we
1442 /// also use `ReVar` -- in that case, the index is used to index into
1443 /// the NLL region checker's data structures. The variable may in fact
1444 /// represent either a free region or an inference variable, in that
1447 /// ## Bound Regions
1449 /// These are regions that are stored behind a binder and must be substituted
1450 /// with some concrete region before being used. There are two kind of
1451 /// bound regions: early-bound, which are bound in an item's `Generics`,
1452 /// and are substituted by an `InternalSubsts`, and late-bound, which are part of
1453 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1454 /// the likes of `liberate_late_bound_regions`. The distinction exists
1455 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1457 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1458 /// outside their binder, e.g., in types passed to type inference, and
1459 /// should first be substituted (by placeholder regions, free regions,
1460 /// or region variables).
1462 /// ## Placeholder and Free Regions
1464 /// One often wants to work with bound regions without knowing their precise
1465 /// identity. For example, when checking a function, the lifetime of a borrow
1466 /// can end up being assigned to some region parameter. In these cases,
1467 /// it must be ensured that bounds on the region can't be accidentally
1468 /// assumed without being checked.
1470 /// To do this, we replace the bound regions with placeholder markers,
1471 /// which don't satisfy any relation not explicitly provided.
1473 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1474 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1475 /// to be used. These also support explicit bounds: both the internally-stored
1476 /// *scope*, which the region is assumed to outlive, as well as other
1477 /// relations stored in the `FreeRegionMap`. Note that these relations
1478 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1479 /// `resolve_regions_and_report_errors`.
1481 /// When working with higher-ranked types, some region relations aren't
1482 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1483 /// `RePlaceholder` is designed for this purpose. In these contexts,
1484 /// there's also the risk that some inference variable laying around will
1485 /// get unified with your placeholder region: if you want to check whether
1486 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1487 /// with a placeholder region `'%a`, the variable `'_` would just be
1488 /// instantiated to the placeholder region `'%a`, which is wrong because
1489 /// the inference variable is supposed to satisfy the relation
1490 /// *for every value of the placeholder region*. To ensure that doesn't
1491 /// happen, you can use `leak_check`. This is more clearly explained
1492 /// by the [rustc dev guide].
1494 /// [1]: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1495 /// [2]: https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1496 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
1497 #[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)]
1498 pub enum RegionKind {
1499 /// Region bound in a type or fn declaration which will be
1500 /// substituted 'early' -- that is, at the same time when type
1501 /// parameters are substituted.
1502 ReEarlyBound(EarlyBoundRegion),
1504 /// Region bound in a function scope, which will be substituted when the
1505 /// function is called.
1506 ReLateBound(ty::DebruijnIndex, BoundRegion),
1508 /// When checking a function body, the types of all arguments and so forth
1509 /// that refer to bound region parameters are modified to refer to free
1510 /// region parameters.
1513 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1516 /// A region variable. Should not exist outside of type inference.
1519 /// A placeholder region -- basically, the higher-ranked version of `ReFree`.
1520 /// Should not exist outside of type inference.
1521 RePlaceholder(ty::PlaceholderRegion),
1523 /// Empty lifetime is for data that is never accessed. We tag the
1524 /// empty lifetime with a universe -- the idea is that we don't
1525 /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable.
1526 /// Therefore, the `'empty` in a universe `U` is less than all
1527 /// regions visible from `U`, but not less than regions not visible
1529 ReEmpty(ty::UniverseIndex),
1531 /// Erased region, used by trait selection, in MIR and during codegen.
1535 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
1536 pub struct EarlyBoundRegion {
1542 /// A **`const`** **v**ariable **ID**.
1543 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1544 pub struct ConstVid<'tcx> {
1546 pub phantom: PhantomData<&'tcx ()>,
1549 rustc_index::newtype_index! {
1550 /// A **region** (lifetime) **v**ariable **ID**.
1551 pub struct RegionVid {
1552 DEBUG_FORMAT = custom,
1556 impl Atom for RegionVid {
1557 fn index(self) -> usize {
1562 rustc_index::newtype_index! {
1563 pub struct BoundVar { .. }
1566 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1567 #[derive(HashStable)]
1568 pub struct BoundTy {
1570 pub kind: BoundTyKind,
1573 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1574 #[derive(HashStable)]
1575 pub enum BoundTyKind {
1580 impl From<BoundVar> for BoundTy {
1581 fn from(var: BoundVar) -> Self {
1582 BoundTy { var, kind: BoundTyKind::Anon }
1586 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1587 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1588 #[derive(HashStable, TypeFoldable)]
1589 pub struct ExistentialProjection<'tcx> {
1590 pub item_def_id: DefId,
1591 pub substs: SubstsRef<'tcx>,
1592 pub term: Term<'tcx>,
1595 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1597 impl<'tcx> ExistentialProjection<'tcx> {
1598 /// Extracts the underlying existential trait reference from this projection.
1599 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1600 /// then this function would return an `exists T. T: Iterator` existential trait
1602 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1603 let def_id = tcx.associated_item(self.item_def_id).container.id();
1604 let subst_count = tcx.generics_of(def_id).count() - 1;
1605 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1606 ty::ExistentialTraitRef { def_id, substs }
1609 pub fn with_self_ty(
1613 ) -> ty::ProjectionPredicate<'tcx> {
1614 // otherwise the escaping regions would be captured by the binders
1615 debug_assert!(!self_ty.has_escaping_bound_vars());
1617 ty::ProjectionPredicate {
1618 projection_ty: ty::ProjectionTy {
1619 item_def_id: self.item_def_id,
1620 substs: tcx.mk_substs_trait(self_ty, self.substs),
1626 pub fn erase_self_ty(
1628 projection_predicate: ty::ProjectionPredicate<'tcx>,
1630 // Assert there is a Self.
1631 projection_predicate.projection_ty.substs.type_at(0);
1634 item_def_id: projection_predicate.projection_ty.item_def_id,
1635 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1636 term: projection_predicate.term,
1641 impl<'tcx> PolyExistentialProjection<'tcx> {
1642 pub fn with_self_ty(
1646 ) -> ty::PolyProjectionPredicate<'tcx> {
1647 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1650 pub fn item_def_id(&self) -> DefId {
1651 self.skip_binder().item_def_id
1655 /// Region utilities
1657 /// Is this region named by the user?
1658 pub fn has_name(&self) -> bool {
1660 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1661 RegionKind::ReLateBound(_, br) => br.kind.is_named(),
1662 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1663 RegionKind::ReStatic => true,
1664 RegionKind::ReVar(..) => false,
1665 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1666 RegionKind::ReEmpty(_) => false,
1667 RegionKind::ReErased => false,
1672 pub fn is_late_bound(&self) -> bool {
1673 matches!(*self, ty::ReLateBound(..))
1677 pub fn is_placeholder(&self) -> bool {
1678 matches!(*self, ty::RePlaceholder(..))
1682 pub fn bound_at_or_above_binder(&self, index: ty::DebruijnIndex) -> bool {
1684 ty::ReLateBound(debruijn, _) => debruijn >= index,
1689 pub fn type_flags(&self) -> TypeFlags {
1690 let mut flags = TypeFlags::empty();
1694 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1695 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1696 flags = flags | TypeFlags::HAS_RE_INFER;
1698 ty::RePlaceholder(..) => {
1699 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1700 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1701 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1703 ty::ReEarlyBound(..) => {
1704 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1705 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1706 flags = flags | TypeFlags::HAS_RE_PARAM;
1708 ty::ReFree { .. } => {
1709 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1710 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1712 ty::ReEmpty(_) | ty::ReStatic => {
1713 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1715 ty::ReLateBound(..) => {
1716 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1719 flags = flags | TypeFlags::HAS_RE_ERASED;
1723 debug!("type_flags({:?}) = {:?}", self, flags);
1728 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1729 /// For example, consider the regions in this snippet of code:
1733 /// ^^ -- early bound, declared on an impl
1735 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1736 /// ^^ ^^ ^ anonymous, late-bound
1737 /// | early-bound, appears in where-clauses
1738 /// late-bound, appears only in fn args
1743 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1744 /// of the impl, and for all the other highlighted regions, it
1745 /// would return the `DefId` of the function. In other cases (not shown), this
1746 /// function might return the `DefId` of a closure.
1747 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId {
1749 ty::ReEarlyBound(br) => tcx.parent(br.def_id).unwrap(),
1750 ty::ReFree(fr) => fr.scope,
1751 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1757 impl<'tcx> TyS<'tcx> {
1759 pub fn kind(&self) -> &TyKind<'tcx> {
1764 pub fn flags(&self) -> TypeFlags {
1769 pub fn is_unit(&self) -> bool {
1771 Tuple(ref tys) => tys.is_empty(),
1777 pub fn is_never(&self) -> bool {
1778 matches!(self.kind(), Never)
1782 pub fn is_primitive(&self) -> bool {
1783 self.kind().is_primitive()
1787 pub fn is_adt(&self) -> bool {
1788 matches!(self.kind(), Adt(..))
1792 pub fn is_ref(&self) -> bool {
1793 matches!(self.kind(), Ref(..))
1797 pub fn is_ty_var(&self) -> bool {
1798 matches!(self.kind(), Infer(TyVar(_)))
1802 pub fn ty_vid(&self) -> Option<ty::TyVid> {
1804 &Infer(TyVar(vid)) => Some(vid),
1810 pub fn is_ty_infer(&self) -> bool {
1811 matches!(self.kind(), Infer(_))
1815 pub fn is_phantom_data(&self) -> bool {
1816 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1820 pub fn is_bool(&self) -> bool {
1821 *self.kind() == Bool
1824 /// Returns `true` if this type is a `str`.
1826 pub fn is_str(&self) -> bool {
1831 pub fn is_param(&self, index: u32) -> bool {
1833 ty::Param(ref data) => data.index == index,
1839 pub fn is_slice(&self) -> bool {
1841 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_) | Str),
1847 pub fn is_array(&self) -> bool {
1848 matches!(self.kind(), Array(..))
1852 pub fn is_simd(&self) -> bool {
1854 Adt(def, _) => def.repr.simd(),
1859 pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1861 Array(ty, _) | Slice(ty) => ty,
1862 Str => tcx.types.u8,
1863 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1867 pub fn expect_opaque_type(&self) -> ty::OpaqueTypeKey<'tcx> {
1868 match *self.kind() {
1869 Opaque(def_id, substs) => ty::OpaqueTypeKey { def_id, substs },
1870 _ => bug!("`expect_opaque_type` called on non-opaque type: {}", self),
1874 pub fn simd_size_and_type(&self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1876 Adt(def, substs) => {
1877 assert!(def.repr.simd(), "`simd_size_and_type` called on non-SIMD type");
1878 let variant = def.non_enum_variant();
1879 let f0_ty = variant.fields[0].ty(tcx, substs);
1881 match f0_ty.kind() {
1882 // If the first field is an array, we assume it is the only field and its
1883 // elements are the SIMD components.
1884 Array(f0_elem_ty, f0_len) => {
1885 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1886 // The way we evaluate the `N` in `[T; N]` here only works since we use
1887 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1888 // if we use it in generic code. See the `simd-array-trait` ui test.
1889 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, f0_elem_ty)
1891 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1892 // all have the same type).
1893 _ => (variant.fields.len() as u64, f0_ty),
1896 _ => bug!("`simd_size_and_type` called on invalid type"),
1901 pub fn is_region_ptr(&self) -> bool {
1902 matches!(self.kind(), Ref(..))
1906 pub fn is_mutable_ptr(&self) -> bool {
1909 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1910 | Ref(_, _, hir::Mutability::Mut)
1914 /// Get the mutability of the reference or `None` when not a reference
1916 pub fn ref_mutability(&self) -> Option<hir::Mutability> {
1918 Ref(_, _, mutability) => Some(*mutability),
1924 pub fn is_unsafe_ptr(&self) -> bool {
1925 matches!(self.kind(), RawPtr(_))
1928 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1930 pub fn is_any_ptr(&self) -> bool {
1931 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1935 pub fn is_box(&self) -> bool {
1937 Adt(def, _) => def.is_box(),
1942 /// Panics if called on any type other than `Box<T>`.
1943 pub fn boxed_ty(&self) -> Ty<'tcx> {
1945 Adt(def, substs) if def.is_box() => substs.type_at(0),
1946 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1950 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1951 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1952 /// contents are abstract to rustc.)
1954 pub fn is_scalar(&self) -> bool {
1964 | Infer(IntVar(_) | FloatVar(_))
1968 /// Returns `true` if this type is a floating point type.
1970 pub fn is_floating_point(&self) -> bool {
1971 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1975 pub fn is_trait(&self) -> bool {
1976 matches!(self.kind(), Dynamic(..))
1980 pub fn is_enum(&self) -> bool {
1981 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1985 pub fn is_union(&self) -> bool {
1986 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1990 pub fn is_closure(&self) -> bool {
1991 matches!(self.kind(), Closure(..))
1995 pub fn is_generator(&self) -> bool {
1996 matches!(self.kind(), Generator(..))
2000 pub fn is_integral(&self) -> bool {
2001 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
2005 pub fn is_fresh_ty(&self) -> bool {
2006 matches!(self.kind(), Infer(FreshTy(_)))
2010 pub fn is_fresh(&self) -> bool {
2011 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
2015 pub fn is_char(&self) -> bool {
2016 matches!(self.kind(), Char)
2020 pub fn is_numeric(&self) -> bool {
2021 self.is_integral() || self.is_floating_point()
2025 pub fn is_signed(&self) -> bool {
2026 matches!(self.kind(), Int(_))
2030 pub fn is_ptr_sized_integral(&self) -> bool {
2031 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
2035 pub fn has_concrete_skeleton(&self) -> bool {
2036 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
2039 /// Returns the type and mutability of `*ty`.
2041 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2042 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2043 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2045 Adt(def, _) if def.is_box() => {
2046 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
2048 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl: *mutbl }),
2049 RawPtr(mt) if explicit => Some(*mt),
2054 /// Returns the type of `ty[i]`.
2055 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2057 Array(ty, _) | Slice(ty) => Some(ty),
2062 pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2064 FnDef(def_id, substs) => tcx.fn_sig(*def_id).subst(tcx, substs),
2067 // ignore errors (#54954)
2068 ty::Binder::dummy(FnSig::fake())
2070 Closure(..) => bug!(
2071 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
2073 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
2078 pub fn is_fn(&self) -> bool {
2079 matches!(self.kind(), FnDef(..) | FnPtr(_))
2083 pub fn is_fn_ptr(&self) -> bool {
2084 matches!(self.kind(), FnPtr(_))
2088 pub fn is_impl_trait(&self) -> bool {
2089 matches!(self.kind(), Opaque(..))
2093 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
2095 Adt(adt, _) => Some(adt),
2100 /// Iterates over tuple fields.
2101 /// Panics when called on anything but a tuple.
2102 pub fn tuple_fields(&self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> {
2104 Tuple(substs) => substs.iter().map(|field| field.expect_ty()),
2105 _ => bug!("tuple_fields called on non-tuple"),
2109 /// Get the `i`-th element of a tuple.
2110 /// Panics when called on anything but a tuple.
2111 pub fn tuple_element_ty(&self, i: usize) -> Option<Ty<'tcx>> {
2113 Tuple(substs) => substs.iter().nth(i).map(|field| field.expect_ty()),
2114 _ => bug!("tuple_fields called on non-tuple"),
2118 /// If the type contains variants, returns the valid range of variant indices.
2120 // FIXME: This requires the optimized MIR in the case of generators.
2122 pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2124 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2125 TyKind::Generator(def_id, substs, _) => {
2126 Some(substs.as_generator().variant_range(*def_id, tcx))
2132 /// If the type contains variants, returns the variant for `variant_index`.
2133 /// Panics if `variant_index` is out of range.
2135 // FIXME: This requires the optimized MIR in the case of generators.
2137 pub fn discriminant_for_variant(
2140 variant_index: VariantIdx,
2141 ) -> Option<Discr<'tcx>> {
2143 TyKind::Adt(adt, _) if adt.variants.is_empty() => {
2144 // This can actually happen during CTFE, see
2145 // https://github.com/rust-lang/rust/issues/89765.
2148 TyKind::Adt(adt, _) if adt.is_enum() => {
2149 Some(adt.discriminant_for_variant(tcx, variant_index))
2151 TyKind::Generator(def_id, substs, _) => {
2152 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2158 /// Returns the type of the discriminant of this type.
2159 pub fn discriminant_ty(&'tcx self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2161 ty::Adt(adt, _) if adt.is_enum() => adt.repr.discr_type().to_ty(tcx),
2162 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2164 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2165 let assoc_items = tcx.associated_item_def_ids(
2166 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2168 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2187 | ty::GeneratorWitness(..)
2191 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2194 | ty::Placeholder(_)
2195 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2196 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2201 /// Returns the type of metadata for (potentially fat) pointers to this type.
2202 pub fn ptr_metadata_ty(
2205 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2207 let tail = tcx.struct_tail_with_normalize(self, normalize);
2210 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2221 | ty::GeneratorWitness(..)
2227 // If returned by `struct_tail_without_normalization` this is a unit struct
2228 // without any fields, or not a struct, and therefore is Sized.
2230 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2231 // a.k.a. unit type, which is Sized
2232 | ty::Tuple(..) => tcx.types.unit,
2234 ty::Str | ty::Slice(_) => tcx.types.usize,
2235 ty::Dynamic(..) => {
2236 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2237 tcx.type_of(dyn_metadata).subst(tcx, &[tail.into()])
2243 | ty::Infer(ty::TyVar(_))
2245 | ty::Placeholder(..)
2246 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2247 bug!("`ptr_metadata_ty` applied to unexpected type: {:?}", tail)
2252 /// When we create a closure, we record its kind (i.e., what trait
2253 /// it implements) into its `ClosureSubsts` using a type
2254 /// parameter. This is kind of a phantom type, except that the
2255 /// most convenient thing for us to are the integral types. This
2256 /// function converts such a special type into the closure
2257 /// kind. To go the other way, use
2258 /// `tcx.closure_kind_ty(closure_kind)`.
2260 /// Note that during type checking, we use an inference variable
2261 /// to represent the closure kind, because it has not yet been
2262 /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
2263 /// is complete, that type variable will be unified.
2264 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2266 Int(int_ty) => match int_ty {
2267 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2268 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2269 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2270 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2273 // "Bound" types appear in canonical queries when the
2274 // closure type is not yet known
2275 Bound(..) | Infer(_) => None,
2277 Error(_) => Some(ty::ClosureKind::Fn),
2279 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2283 /// Fast path helper for testing if a type is `Sized`.
2285 /// Returning true means the type is known to be sized. Returning
2286 /// `false` means nothing -- could be sized, might not be.
2288 /// Note that we could never rely on the fact that a type such as `[_]` is
2289 /// trivially `!Sized` because we could be in a type environment with a
2290 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2291 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2292 /// this method doesn't return `Option<bool>`.
2293 pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool {
2295 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2306 | ty::GeneratorWitness(..)
2310 | ty::Error(_) => true,
2312 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2314 ty::Tuple(tys) => tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx)),
2316 ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(),
2318 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2320 ty::Infer(ty::TyVar(_)) => false,
2323 | ty::Placeholder(..)
2324 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2325 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2331 /// Extra information about why we ended up with a particular variance.
2332 /// This is only used to add more information to error messages, and
2333 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2334 /// may lead to confusing notes in error messages, it will never cause
2335 /// a miscompilation or unsoundness.
2337 /// When in doubt, use `VarianceDiagInfo::default()`
2338 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2339 pub enum VarianceDiagInfo<'tcx> {
2340 /// No additional information - this is the default.
2341 /// We will not add any additional information to error messages.
2344 /// We switched our variance because a generic argument occurs inside
2345 /// the invariant generic argument of another type.
2347 /// The generic type containing the generic parameter
2348 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2350 /// The index of the generic parameter being used
2351 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2356 impl<'tcx> VarianceDiagInfo<'tcx> {
2357 /// Mirrors `Variance::xform` - used to 'combine' the existing
2358 /// and new `VarianceDiagInfo`s when our variance changes.
2359 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2360 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2362 VarianceDiagInfo::None => other,
2363 VarianceDiagInfo::Invariant { .. } => self,