1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
5 use crate::infer::canonical::Canonical;
6 use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
7 use crate::ty::visit::ValidateBoundVars;
8 use crate::ty::InferTy::*;
10 self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeSuperVisitable, TypeVisitable,
13 use crate::ty::{List, ParamEnv};
14 use hir::def::DefKind;
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, sym, Symbol};
24 use rustc_target::abi::VariantIdx;
25 use rustc_target::spec::abi;
27 use std::cmp::Ordering;
29 use std::marker::PhantomData;
30 use std::ops::{ControlFlow, Deref, Range};
31 use ty::util::IntTypeExt;
33 use rustc_type_ir::sty::TyKind::*;
34 use rustc_type_ir::RegionKind as IrRegionKind;
35 use rustc_type_ir::TyKind as IrTyKind;
37 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
38 #[rustc_diagnostic_item = "TyKind"]
39 pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
40 pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
42 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
43 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
44 pub struct TypeAndMut<'tcx> {
46 pub mutbl: hir::Mutability,
49 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
51 /// A "free" region `fr` can be interpreted as "some region
52 /// at least as big as the scope `fr.scope`".
53 pub struct FreeRegion {
55 pub bound_region: BoundRegionKind,
58 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
60 pub enum BoundRegionKind {
61 /// An anonymous region parameter for a given fn (&T)
62 BrAnon(u32, Option<Span>),
64 /// Named region parameters for functions (a in &'a T)
66 /// The `DefId` is needed to distinguish free regions in
67 /// the event of shadowing.
68 BrNamed(DefId, Symbol),
70 /// Anonymous region for the implicit env pointer parameter
75 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
77 pub struct BoundRegion {
79 pub kind: BoundRegionKind,
82 impl BoundRegionKind {
83 pub fn is_named(&self) -> bool {
85 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
90 pub fn get_name(&self) -> Option<Symbol> {
93 BoundRegionKind::BrNamed(_, name) => return Some(name),
103 fn article(&self) -> &'static str;
106 impl<'tcx> Article for TyKind<'tcx> {
107 /// Get the article ("a" or "an") to use with this type.
108 fn article(&self) -> &'static str {
110 Int(_) | Float(_) | Array(_, _) => "an",
111 Adt(def, _) if def.is_enum() => "an",
112 // This should never happen, but ICEing and causing the user's code
113 // to not compile felt too harsh.
120 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
121 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
122 static_assert_size!(TyKind<'_>, 32);
124 /// A closure can be modeled as a struct that looks like:
125 /// ```ignore (illustrative)
126 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
130 /// - 'l0...'li and T0...Tj are the generic parameters
131 /// in scope on the function that defined the closure,
132 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
133 /// is rather hackily encoded via a scalar type. See
134 /// `Ty::to_opt_closure_kind` for details.
135 /// - CS represents the *closure signature*, representing as a `fn()`
136 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
137 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
139 /// - U is a type parameter representing the types of its upvars, tupled up
140 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
141 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
143 /// So, for example, given this function:
144 /// ```ignore (illustrative)
145 /// fn foo<'a, T>(data: &'a mut T) {
146 /// do(|| data.count += 1)
149 /// the type of the closure would be something like:
150 /// ```ignore (illustrative)
151 /// struct Closure<'a, T, U>(...U);
153 /// Note that the type of the upvar is not specified in the struct.
154 /// You may wonder how the impl would then be able to use the upvar,
155 /// if it doesn't know it's type? The answer is that the impl is
156 /// (conceptually) not fully generic over Closure but rather tied to
157 /// instances with the expected upvar types:
158 /// ```ignore (illustrative)
159 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
163 /// You can see that the *impl* fully specified the type of the upvar
164 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
165 /// (Here, I am assuming that `data` is mut-borrowed.)
167 /// Now, the last question you may ask is: Why include the upvar types
168 /// in an extra type parameter? The reason for this design is that the
169 /// upvar types can reference lifetimes that are internal to the
170 /// creating function. In my example above, for example, the lifetime
171 /// `'b` represents the scope of the closure itself; this is some
172 /// subset of `foo`, probably just the scope of the call to the to
173 /// `do()`. If we just had the lifetime/type parameters from the
174 /// enclosing function, we couldn't name this lifetime `'b`. Note that
175 /// there can also be lifetimes in the types of the upvars themselves,
176 /// if one of them happens to be a reference to something that the
177 /// creating fn owns.
179 /// OK, you say, so why not create a more minimal set of parameters
180 /// that just includes the extra lifetime parameters? The answer is
181 /// primarily that it would be hard --- we don't know at the time when
182 /// we create the closure type what the full types of the upvars are,
183 /// nor do we know which are borrowed and which are not. In this
184 /// design, we can just supply a fresh type parameter and figure that
187 /// All right, you say, but why include the type parameters from the
188 /// original function then? The answer is that codegen may need them
189 /// when monomorphizing, and they may not appear in the upvars. A
190 /// closure could capture no variables but still make use of some
191 /// in-scope type parameter with a bound (e.g., if our example above
192 /// had an extra `U: Default`, and the closure called `U::default()`).
194 /// There is another reason. This design (implicitly) prohibits
195 /// closures from capturing themselves (except via a trait
196 /// object). This simplifies closure inference considerably, since it
197 /// means that when we infer the kind of a closure or its upvars, we
198 /// don't have to handle cycles where the decisions we make for
199 /// closure C wind up influencing the decisions we ought to make for
200 /// closure C (which would then require fixed point iteration to
201 /// handle). Plus it fixes an ICE. :P
205 /// Generators are handled similarly in `GeneratorSubsts`. The set of
206 /// type parameters is similar, but `CK` and `CS` are replaced by the
207 /// following type parameters:
209 /// * `GS`: The generator's "resume type", which is the type of the
210 /// argument passed to `resume`, and the type of `yield` expressions
211 /// inside the generator.
212 /// * `GY`: The "yield type", which is the type of values passed to
213 /// `yield` inside the generator.
214 /// * `GR`: The "return type", which is the type of value returned upon
215 /// completion of the generator.
216 /// * `GW`: The "generator witness".
217 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
218 pub struct ClosureSubsts<'tcx> {
219 /// Lifetime and type parameters from the enclosing function,
220 /// concatenated with a tuple containing the types of the upvars.
222 /// These are separated out because codegen wants to pass them around
223 /// when monomorphizing.
224 pub substs: SubstsRef<'tcx>,
227 /// Struct returned by `split()`.
228 pub struct ClosureSubstsParts<'tcx, T> {
229 pub parent_substs: &'tcx [GenericArg<'tcx>],
230 pub closure_kind_ty: T,
231 pub closure_sig_as_fn_ptr_ty: T,
232 pub tupled_upvars_ty: T,
235 impl<'tcx> ClosureSubsts<'tcx> {
236 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
237 /// for the closure parent, alongside additional closure-specific components.
240 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
241 ) -> ClosureSubsts<'tcx> {
243 substs: tcx.mk_substs(
244 parts.parent_substs.iter().copied().chain(
245 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
247 .map(|&ty| ty.into()),
253 /// Divides the closure substs into their respective components.
254 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
255 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
256 match self.substs[..] {
258 ref parent_substs @ ..,
260 closure_sig_as_fn_ptr_ty,
262 ] => ClosureSubstsParts {
265 closure_sig_as_fn_ptr_ty,
268 _ => bug!("closure substs missing synthetics"),
272 /// Returns `true` only if enough of the synthetic types are known to
273 /// allow using all of the methods on `ClosureSubsts` without panicking.
275 /// Used primarily by `ty::print::pretty` to be able to handle closure
276 /// types that haven't had their synthetic types substituted in.
277 pub fn is_valid(self) -> bool {
278 self.substs.len() >= 3
279 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
282 /// Returns the substitutions of the closure's parent.
283 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
284 self.split().parent_substs
287 /// Returns an iterator over the list of types of captured paths by the closure.
288 /// In case there was a type error in figuring out the types of the captured path, an
289 /// empty iterator is returned.
291 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
292 match self.tupled_upvars_ty().kind() {
293 TyKind::Error(_) => None,
294 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
295 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
296 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
302 /// Returns the tuple type representing the upvars for this closure.
304 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
305 self.split().tupled_upvars_ty.expect_ty()
308 /// Returns the closure kind for this closure; may return a type
309 /// variable during inference. To get the closure kind during
310 /// inference, use `infcx.closure_kind(substs)`.
311 pub fn kind_ty(self) -> Ty<'tcx> {
312 self.split().closure_kind_ty.expect_ty()
315 /// Returns the `fn` pointer type representing the closure signature for this
317 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
318 // type is known at the time of the creation of `ClosureSubsts`,
319 // see `rustc_hir_analysis::check::closure`.
320 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
321 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
324 /// Returns the closure kind for this closure; only usable outside
325 /// of an inference context, because in that context we know that
326 /// there are no type variables.
328 /// If you have an inference context, use `infcx.closure_kind()`.
329 pub fn kind(self) -> ty::ClosureKind {
330 self.kind_ty().to_opt_closure_kind().unwrap()
333 /// Extracts the signature from the closure.
334 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
335 let ty = self.sig_as_fn_ptr_ty();
337 ty::FnPtr(sig) => *sig,
338 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
342 pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
343 ty::print::PrintClosureAsImpl { closure: self }
347 /// Similar to `ClosureSubsts`; see the above documentation for more.
348 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
349 pub struct GeneratorSubsts<'tcx> {
350 pub substs: SubstsRef<'tcx>,
353 pub struct GeneratorSubstsParts<'tcx, T> {
354 pub parent_substs: &'tcx [GenericArg<'tcx>],
359 pub tupled_upvars_ty: T,
362 impl<'tcx> GeneratorSubsts<'tcx> {
363 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
364 /// for the generator parent, alongside additional generator-specific components.
367 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
368 ) -> GeneratorSubsts<'tcx> {
370 substs: tcx.mk_substs(
371 parts.parent_substs.iter().copied().chain(
377 parts.tupled_upvars_ty,
380 .map(|&ty| ty.into()),
386 /// Divides the generator substs into their respective components.
387 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
388 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
389 match self.substs[..] {
390 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
391 GeneratorSubstsParts {
400 _ => bug!("generator substs missing synthetics"),
404 /// Returns `true` only if enough of the synthetic types are known to
405 /// allow using all of the methods on `GeneratorSubsts` without panicking.
407 /// Used primarily by `ty::print::pretty` to be able to handle generator
408 /// types that haven't had their synthetic types substituted in.
409 pub fn is_valid(self) -> bool {
410 self.substs.len() >= 5
411 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
414 /// Returns the substitutions of the generator's parent.
415 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
416 self.split().parent_substs
419 /// This describes the types that can be contained in a generator.
420 /// It will be a type variable initially and unified in the last stages of typeck of a body.
421 /// It contains a tuple of all the types that could end up on a generator frame.
422 /// The state transformation MIR pass may only produce layouts which mention types
423 /// in this tuple. Upvars are not counted here.
424 pub fn witness(self) -> Ty<'tcx> {
425 self.split().witness.expect_ty()
428 /// Returns an iterator over the list of types of captured paths by the generator.
429 /// In case there was a type error in figuring out the types of the captured path, an
430 /// empty iterator is returned.
432 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
433 match self.tupled_upvars_ty().kind() {
434 TyKind::Error(_) => None,
435 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
436 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
437 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
443 /// Returns the tuple type representing the upvars for this generator.
445 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
446 self.split().tupled_upvars_ty.expect_ty()
449 /// Returns the type representing the resume type of the generator.
450 pub fn resume_ty(self) -> Ty<'tcx> {
451 self.split().resume_ty.expect_ty()
454 /// Returns the type representing the yield type of the generator.
455 pub fn yield_ty(self) -> Ty<'tcx> {
456 self.split().yield_ty.expect_ty()
459 /// Returns the type representing the return type of the generator.
460 pub fn return_ty(self) -> Ty<'tcx> {
461 self.split().return_ty.expect_ty()
464 /// Returns the "generator signature", which consists of its yield
465 /// and return types.
467 /// N.B., some bits of the code prefers to see this wrapped in a
468 /// binder, but it never contains bound regions. Probably this
469 /// function should be removed.
470 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
471 ty::Binder::dummy(self.sig())
474 /// Returns the "generator signature", which consists of its resume, yield
475 /// and return types.
476 pub fn sig(self) -> GenSig<'tcx> {
478 resume_ty: self.resume_ty(),
479 yield_ty: self.yield_ty(),
480 return_ty: self.return_ty(),
485 impl<'tcx> GeneratorSubsts<'tcx> {
486 /// Generator has not been resumed yet.
487 pub const UNRESUMED: usize = 0;
488 /// Generator has returned or is completed.
489 pub const RETURNED: usize = 1;
490 /// Generator has been poisoned.
491 pub const POISONED: usize = 2;
493 const UNRESUMED_NAME: &'static str = "Unresumed";
494 const RETURNED_NAME: &'static str = "Returned";
495 const POISONED_NAME: &'static str = "Panicked";
497 /// The valid variant indices of this generator.
499 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
500 // FIXME requires optimized MIR
501 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
502 VariantIdx::new(0)..VariantIdx::new(num_variants)
505 /// The discriminant for the given variant. Panics if the `variant_index` is
508 pub fn discriminant_for_variant(
512 variant_index: VariantIdx,
514 // Generators don't support explicit discriminant values, so they are
515 // the same as the variant index.
516 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
517 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
520 /// The set of all discriminants for the generator, enumerated with their
523 pub fn discriminants(
527 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
528 self.variant_range(def_id, tcx).map(move |index| {
529 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
533 /// Calls `f` with a reference to the name of the enumerator for the given
535 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
537 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
538 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
539 Self::POISONED => Cow::from(Self::POISONED_NAME),
540 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
544 /// The type of the state discriminant used in the generator type.
546 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
550 /// This returns the types of the MIR locals which had to be stored across suspension points.
551 /// It is calculated in rustc_mir_transform::generator::StateTransform.
552 /// All the types here must be in the tuple in GeneratorInterior.
554 /// The locals are grouped by their variant number. Note that some locals may
555 /// be repeated in multiple variants.
561 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
562 let layout = tcx.generator_layout(def_id).unwrap();
563 layout.variant_fields.iter().map(move |variant| {
566 .map(move |field| ty::EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
570 /// This is the types of the fields of a generator which are not stored in a
573 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
578 #[derive(Debug, Copy, Clone, HashStable)]
579 pub enum UpvarSubsts<'tcx> {
580 Closure(SubstsRef<'tcx>),
581 Generator(SubstsRef<'tcx>),
584 impl<'tcx> UpvarSubsts<'tcx> {
585 /// Returns an iterator over the list of types of captured paths by the closure/generator.
586 /// In case there was a type error in figuring out the types of the captured path, an
587 /// empty iterator is returned.
589 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
590 let tupled_tys = match self {
591 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
592 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
595 match tupled_tys.kind() {
596 TyKind::Error(_) => None,
597 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
598 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
599 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
606 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
608 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
609 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
614 /// An inline const is modeled like
615 /// ```ignore (illustrative)
616 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
620 /// - 'l0...'li and T0...Tj are the generic parameters
621 /// inherited from the item that defined the inline const,
622 /// - R represents the type of the constant.
624 /// When the inline const is instantiated, `R` is substituted as the actual inferred
625 /// type of the constant. The reason that `R` is represented as an extra type parameter
626 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
627 /// inline const can reference lifetimes that are internal to the creating function.
628 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
629 pub struct InlineConstSubsts<'tcx> {
630 /// Generic parameters from the enclosing item,
631 /// concatenated with the inferred type of the constant.
632 pub substs: SubstsRef<'tcx>,
635 /// Struct returned by `split()`.
636 pub struct InlineConstSubstsParts<'tcx, T> {
637 pub parent_substs: &'tcx [GenericArg<'tcx>],
641 impl<'tcx> InlineConstSubsts<'tcx> {
642 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
645 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
646 ) -> InlineConstSubsts<'tcx> {
648 substs: tcx.mk_substs(
649 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
654 /// Divides the inline const substs into their respective components.
655 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
656 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
657 match self.substs[..] {
658 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
659 _ => bug!("inline const substs missing synthetics"),
663 /// Returns the substitutions of the inline const's parent.
664 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
665 self.split().parent_substs
668 /// Returns the type of this inline const.
669 pub fn ty(self) -> Ty<'tcx> {
670 self.split().ty.expect_ty()
674 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
675 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
676 pub enum ExistentialPredicate<'tcx> {
677 /// E.g., `Iterator`.
678 Trait(ExistentialTraitRef<'tcx>),
679 /// E.g., `Iterator::Item = T`.
680 Projection(ExistentialProjection<'tcx>),
685 impl<'tcx> ExistentialPredicate<'tcx> {
686 /// Compares via an ordering that will not change if modules are reordered or other changes are
687 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
688 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
689 use self::ExistentialPredicate::*;
690 match (*self, *other) {
691 (Trait(_), Trait(_)) => Ordering::Equal,
692 (Projection(ref a), Projection(ref b)) => {
693 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
695 (AutoTrait(ref a), AutoTrait(ref b)) => {
696 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
698 (Trait(_), _) => Ordering::Less,
699 (Projection(_), Trait(_)) => Ordering::Greater,
700 (Projection(_), _) => Ordering::Less,
701 (AutoTrait(_), _) => Ordering::Greater,
706 pub type PolyExistentialPredicate<'tcx> = Binder<'tcx, ExistentialPredicate<'tcx>>;
708 impl<'tcx> PolyExistentialPredicate<'tcx> {
709 /// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
710 /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
711 /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
712 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
713 use crate::ty::ToPredicate;
714 match self.skip_binder() {
715 ExistentialPredicate::Trait(tr) => {
716 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
718 ExistentialPredicate::Projection(p) => {
719 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
721 ExistentialPredicate::AutoTrait(did) => {
722 let trait_ref = self.rebind(tcx.mk_trait_ref(did, [self_ty]));
723 trait_ref.without_const().to_predicate(tcx)
729 impl<'tcx> List<ty::PolyExistentialPredicate<'tcx>> {
730 /// Returns the "principal `DefId`" of this set of existential predicates.
732 /// A Rust trait object type consists (in addition to a lifetime bound)
733 /// of a set of trait bounds, which are separated into any number
734 /// of auto-trait bounds, and at most one non-auto-trait bound. The
735 /// non-auto-trait bound is called the "principal" of the trait
738 /// Only the principal can have methods or type parameters (because
739 /// auto traits can have neither of them). This is important, because
740 /// it means the auto traits can be treated as an unordered set (methods
741 /// would force an order for the vtable, while relating traits with
742 /// type parameters without knowing the order to relate them in is
743 /// a rather non-trivial task).
745 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
746 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
747 /// are the set `{Sync}`.
749 /// It is also possible to have a "trivial" trait object that
750 /// consists only of auto traits, with no principal - for example,
751 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
752 /// is `{Send, Sync}`, while there is no principal. These trait objects
753 /// have a "trivial" vtable consisting of just the size, alignment,
755 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
757 .map_bound(|this| match this {
758 ExistentialPredicate::Trait(tr) => Some(tr),
764 pub fn principal_def_id(&self) -> Option<DefId> {
765 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
769 pub fn projection_bounds<'a>(
771 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
772 self.iter().filter_map(|predicate| {
774 .map_bound(|pred| match pred {
775 ExistentialPredicate::Projection(projection) => Some(projection),
783 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'a {
784 self.iter().filter_map(|predicate| match predicate.skip_binder() {
785 ExistentialPredicate::AutoTrait(did) => Some(did),
791 /// A complete reference to a trait. These take numerous guises in syntax,
792 /// but perhaps the most recognizable form is in a where-clause:
793 /// ```ignore (illustrative)
796 /// This would be represented by a trait-reference where the `DefId` is the
797 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
798 /// and `U` as parameter 1.
800 /// Trait references also appear in object types like `Foo<U>`, but in
801 /// that case the `Self` parameter is absent from the substitutions.
802 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
803 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
804 pub struct TraitRef<'tcx> {
806 pub substs: SubstsRef<'tcx>,
809 impl<'tcx> TraitRef<'tcx> {
810 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
811 TraitRef { def_id, substs }
814 pub fn with_self_type(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
817 [self_ty.into()].into_iter().chain(self.substs.iter().skip(1)),
821 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
822 /// are the parameters defined on trait.
823 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
824 ty::Binder::dummy(TraitRef {
826 substs: InternalSubsts::identity_for_item(tcx, def_id),
831 pub fn self_ty(&self) -> Ty<'tcx> {
832 self.substs.type_at(0)
838 substs: SubstsRef<'tcx>,
839 ) -> ty::TraitRef<'tcx> {
840 let defs = tcx.generics_of(trait_id);
841 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
845 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
847 impl<'tcx> PolyTraitRef<'tcx> {
848 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
849 self.map_bound_ref(|tr| tr.self_ty())
852 pub fn def_id(&self) -> DefId {
853 self.skip_binder().def_id
856 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
857 self.map_bound(|trait_ref| ty::TraitPredicate {
859 constness: ty::BoundConstness::NotConst,
860 polarity: ty::ImplPolarity::Positive,
864 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
865 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
866 self.map_bound(|trait_ref| ty::TraitPredicate {
868 constness: ty::BoundConstness::NotConst,
869 polarity: ty::ImplPolarity::Negative,
874 impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
875 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
876 self.to_string().into_diagnostic_arg()
880 /// An existential reference to a trait, where `Self` is erased.
881 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
882 /// ```ignore (illustrative)
883 /// exists T. T: Trait<'a, 'b, X, Y>
885 /// The substitutions don't include the erased `Self`, only trait
886 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
887 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
888 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
889 pub struct ExistentialTraitRef<'tcx> {
891 pub substs: SubstsRef<'tcx>,
894 impl<'tcx> ExistentialTraitRef<'tcx> {
895 pub fn erase_self_ty(
897 trait_ref: ty::TraitRef<'tcx>,
898 ) -> ty::ExistentialTraitRef<'tcx> {
899 // Assert there is a Self.
900 trait_ref.substs.type_at(0);
902 ty::ExistentialTraitRef {
903 def_id: trait_ref.def_id,
904 substs: tcx.intern_substs(&trait_ref.substs[1..]),
908 /// Object types don't have a self type specified. Therefore, when
909 /// we convert the principal trait-ref into a normal trait-ref,
910 /// you must give *some* self type. A common choice is `mk_err()`
911 /// or some placeholder type.
912 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
913 // otherwise the escaping vars would be captured by the binder
914 // debug_assert!(!self_ty.has_escaping_bound_vars());
916 tcx.mk_trait_ref(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter()))
920 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
922 impl<'tcx> PolyExistentialTraitRef<'tcx> {
923 pub fn def_id(&self) -> DefId {
924 self.skip_binder().def_id
927 /// Object types don't have a self type specified. Therefore, when
928 /// we convert the principal trait-ref into a normal trait-ref,
929 /// you must give *some* self type. A common choice is `mk_err()`
930 /// or some placeholder type.
931 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
932 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
936 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
937 #[derive(HashStable)]
938 pub enum BoundVariableKind {
940 Region(BoundRegionKind),
944 impl BoundVariableKind {
945 pub fn expect_region(self) -> BoundRegionKind {
947 BoundVariableKind::Region(lt) => lt,
948 _ => bug!("expected a region, but found another kind"),
952 pub fn expect_ty(self) -> BoundTyKind {
954 BoundVariableKind::Ty(ty) => ty,
955 _ => bug!("expected a type, but found another kind"),
959 pub fn expect_const(self) {
961 BoundVariableKind::Const => (),
962 _ => bug!("expected a const, but found another kind"),
967 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
968 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
969 /// (which would be represented by the type `PolyTraitRef ==
970 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
971 /// erase, or otherwise "discharge" these bound vars, we change the
972 /// type from `Binder<'tcx, T>` to just `T` (see
973 /// e.g., `liberate_late_bound_regions`).
975 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
976 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
977 #[derive(HashStable, Lift)]
978 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
980 impl<'tcx, T> Binder<'tcx, T>
982 T: TypeVisitable<'tcx>,
984 /// Wraps `value` in a binder, asserting that `value` does not
985 /// contain any bound vars that would be bound by the
986 /// binder. This is commonly used to 'inject' a value T into a
987 /// different binding level.
988 pub fn dummy(value: T) -> Binder<'tcx, T> {
989 assert!(!value.has_escaping_bound_vars());
990 Binder(value, ty::List::empty())
993 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
994 if cfg!(debug_assertions) {
995 let mut validator = ValidateBoundVars::new(vars);
996 value.visit_with(&mut validator);
1002 impl<'tcx, T> Binder<'tcx, T> {
1003 /// Skips the binder and returns the "bound" value. This is a
1004 /// risky thing to do because it's easy to get confused about
1005 /// De Bruijn indices and the like. It is usually better to
1006 /// discharge the binder using `no_bound_vars` or
1007 /// `replace_late_bound_regions` or something like
1008 /// that. `skip_binder` is only valid when you are either
1009 /// extracting data that has nothing to do with bound vars, you
1010 /// are doing some sort of test that does not involve bound
1011 /// regions, or you are being very careful about your depth
1014 /// Some examples where `skip_binder` is reasonable:
1016 /// - extracting the `DefId` from a PolyTraitRef;
1017 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1018 /// a type parameter `X`, since the type `X` does not reference any regions
1019 pub fn skip_binder(self) -> T {
1023 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1027 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1028 Binder(&self.0, self.1)
1031 pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
1035 Binder(&self.0, self.1)
1038 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1042 let value = f(&self.0);
1043 Binder(value, self.1)
1046 pub fn map_bound_ref<F, U: TypeVisitable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1050 self.as_ref().map_bound(f)
1053 pub fn map_bound<F, U: TypeVisitable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1057 let value = f(self.0);
1058 if cfg!(debug_assertions) {
1059 let mut validator = ValidateBoundVars::new(self.1);
1060 value.visit_with(&mut validator);
1062 Binder(value, self.1)
1065 pub fn try_map_bound<F, U: TypeVisitable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1067 F: FnOnce(T) -> Result<U, E>,
1069 let value = f(self.0)?;
1070 if cfg!(debug_assertions) {
1071 let mut validator = ValidateBoundVars::new(self.1);
1072 value.visit_with(&mut validator);
1074 Ok(Binder(value, self.1))
1077 /// Wraps a `value` in a binder, using the same bound variables as the
1078 /// current `Binder`. This should not be used if the new value *changes*
1079 /// the bound variables. Note: the (old or new) value itself does not
1080 /// necessarily need to *name* all the bound variables.
1082 /// This currently doesn't do anything different than `bind`, because we
1083 /// don't actually track bound vars. However, semantically, it is different
1084 /// because bound vars aren't allowed to change here, whereas they are
1085 /// in `bind`. This may be (debug) asserted in the future.
1086 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1088 U: TypeVisitable<'tcx>,
1090 if cfg!(debug_assertions) {
1091 let mut validator = ValidateBoundVars::new(self.bound_vars());
1092 value.visit_with(&mut validator);
1094 Binder(value, self.1)
1097 /// Unwraps and returns the value within, but only if it contains
1098 /// no bound vars at all. (In other words, if this binder --
1099 /// and indeed any enclosing binder -- doesn't bind anything at
1100 /// all.) Otherwise, returns `None`.
1102 /// (One could imagine having a method that just unwraps a single
1103 /// binder, but permits late-bound vars bound by enclosing
1104 /// binders, but that would require adjusting the debruijn
1105 /// indices, and given the shallow binding structure we often use,
1106 /// would not be that useful.)
1107 pub fn no_bound_vars(self) -> Option<T>
1109 T: TypeVisitable<'tcx>,
1111 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1114 /// Splits the contents into two things that share the same binder
1115 /// level as the original, returning two distinct binders.
1117 /// `f` should consider bound regions at depth 1 to be free, and
1118 /// anything it produces with bound regions at depth 1 will be
1119 /// bound in the resulting return values.
1120 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1122 F: FnOnce(T) -> (U, V),
1124 let (u, v) = f(self.0);
1125 (Binder(u, self.1), Binder(v, self.1))
1129 impl<'tcx, T> Binder<'tcx, Option<T>> {
1130 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1131 let bound_vars = self.1;
1132 self.0.map(|v| Binder(v, bound_vars))
1136 /// Represents the projection of an associated type. In explicit UFCS
1137 /// form this would be written `<T as Trait<..>>::N`.
1138 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1139 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1140 pub struct ProjectionTy<'tcx> {
1141 /// The parameters of the associated item.
1142 pub substs: SubstsRef<'tcx>,
1144 /// The `DefId` of the `TraitItem` for the associated type `N`.
1146 /// Note that this is not the `DefId` of the `TraitRef` containing this
1147 /// associated type, which is in `tcx.associated_item(item_def_id).container`,
1148 /// aka. `tcx.parent(item_def_id).unwrap()`.
1149 pub item_def_id: DefId,
1152 impl<'tcx> ProjectionTy<'tcx> {
1153 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1154 match tcx.def_kind(self.item_def_id) {
1155 DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.item_def_id),
1156 DefKind::ImplTraitPlaceholder => {
1157 tcx.parent(tcx.impl_trait_in_trait_parent(self.item_def_id))
1159 kind => bug!("unexpected DefKind in ProjectionTy: {kind:?}"),
1163 /// Extracts the underlying trait reference and own substs from this projection.
1164 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1165 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1166 pub fn trait_ref_and_own_substs(
1169 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1170 let def_id = tcx.parent(self.item_def_id);
1171 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
1172 let trait_generics = tcx.generics_of(def_id);
1174 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1175 &self.substs[trait_generics.count()..],
1179 /// Extracts the underlying trait reference from this projection.
1180 /// For example, if this is a projection of `<T as Iterator>::Item`,
1181 /// then this function would return a `T: Iterator` trait reference.
1183 /// WARNING: This will drop the substs for generic associated types
1184 /// consider calling [Self::trait_ref_and_own_substs] to get those
1186 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1187 let def_id = self.trait_def_id(tcx);
1188 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1191 pub fn self_ty(&self) -> Ty<'tcx> {
1192 self.substs.type_at(0)
1196 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
1197 pub struct GenSig<'tcx> {
1198 pub resume_ty: Ty<'tcx>,
1199 pub yield_ty: Ty<'tcx>,
1200 pub return_ty: Ty<'tcx>,
1203 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1205 /// Signature of a function type, which we have arbitrarily
1206 /// decided to use to refer to the input/output types.
1208 /// - `inputs`: is the list of arguments and their modes.
1209 /// - `output`: is the return type.
1210 /// - `c_variadic`: indicates whether this is a C-variadic function.
1211 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1212 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1213 pub struct FnSig<'tcx> {
1214 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1215 pub c_variadic: bool,
1216 pub unsafety: hir::Unsafety,
1220 impl<'tcx> FnSig<'tcx> {
1221 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1222 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1225 pub fn output(&self) -> Ty<'tcx> {
1226 self.inputs_and_output[self.inputs_and_output.len() - 1]
1229 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1231 fn fake() -> FnSig<'tcx> {
1233 inputs_and_output: List::empty(),
1235 unsafety: hir::Unsafety::Normal,
1236 abi: abi::Abi::Rust,
1241 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1243 impl<'tcx> PolyFnSig<'tcx> {
1245 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1246 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1249 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1250 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1252 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1253 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1256 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1257 self.map_bound_ref(|fn_sig| fn_sig.output())
1259 pub fn c_variadic(&self) -> bool {
1260 self.skip_binder().c_variadic
1262 pub fn unsafety(&self) -> hir::Unsafety {
1263 self.skip_binder().unsafety
1265 pub fn abi(&self) -> abi::Abi {
1266 self.skip_binder().abi
1270 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1272 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1273 #[derive(HashStable)]
1274 pub struct ParamTy {
1279 impl<'tcx> ParamTy {
1280 pub fn new(index: u32, name: Symbol) -> ParamTy {
1281 ParamTy { index, name }
1284 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1285 ParamTy::new(def.index, def.name)
1289 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1290 tcx.mk_ty_param(self.index, self.name)
1293 pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
1294 let generics = tcx.generics_of(item_with_generics);
1295 let type_param = generics.type_param(self, tcx);
1296 tcx.def_span(type_param.def_id)
1300 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1301 #[derive(HashStable)]
1302 pub struct ParamConst {
1308 pub fn new(index: u32, name: Symbol) -> ParamConst {
1309 ParamConst { index, name }
1312 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1313 ParamConst::new(def.index, def.name)
1317 /// Use this rather than `RegionKind`, whenever possible.
1318 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1319 #[rustc_pass_by_value]
1320 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
1322 impl<'tcx> Deref for Region<'tcx> {
1323 type Target = RegionKind<'tcx>;
1326 fn deref(&self) -> &RegionKind<'tcx> {
1331 impl<'tcx> fmt::Debug for Region<'tcx> {
1332 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1333 write!(f, "{:?}", self.kind())
1337 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1338 #[derive(HashStable)]
1339 pub struct EarlyBoundRegion {
1345 impl fmt::Debug for EarlyBoundRegion {
1346 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1347 write!(f, "{}, {}", self.index, self.name)
1351 /// A **`const`** **v**ariable **ID**.
1352 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1353 #[derive(HashStable, TyEncodable, TyDecodable)]
1354 pub struct ConstVid<'tcx> {
1356 pub phantom: PhantomData<&'tcx ()>,
1359 rustc_index::newtype_index! {
1360 /// A **region** (lifetime) **v**ariable **ID**.
1361 #[derive(HashStable)]
1362 pub struct RegionVid {
1363 DEBUG_FORMAT = custom,
1367 impl Atom for RegionVid {
1368 fn index(self) -> usize {
1373 rustc_index::newtype_index! {
1374 #[derive(HashStable)]
1375 pub struct BoundVar { .. }
1378 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1379 #[derive(HashStable)]
1380 pub struct BoundTy {
1382 pub kind: BoundTyKind,
1385 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1386 #[derive(HashStable)]
1387 pub enum BoundTyKind {
1392 impl From<BoundVar> for BoundTy {
1393 fn from(var: BoundVar) -> Self {
1394 BoundTy { var, kind: BoundTyKind::Anon }
1398 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1399 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1400 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1401 pub struct ExistentialProjection<'tcx> {
1402 pub item_def_id: DefId,
1403 pub substs: SubstsRef<'tcx>,
1404 pub term: Term<'tcx>,
1407 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1409 impl<'tcx> ExistentialProjection<'tcx> {
1410 /// Extracts the underlying existential trait reference from this projection.
1411 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1412 /// then this function would return an `exists T. T: Iterator` existential trait
1414 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1415 let def_id = tcx.parent(self.item_def_id);
1416 let subst_count = tcx.generics_of(def_id).count() - 1;
1417 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1418 ty::ExistentialTraitRef { def_id, substs }
1421 pub fn with_self_ty(
1425 ) -> ty::ProjectionPredicate<'tcx> {
1426 // otherwise the escaping regions would be captured by the binders
1427 debug_assert!(!self_ty.has_escaping_bound_vars());
1429 ty::ProjectionPredicate {
1430 projection_ty: ty::ProjectionTy {
1431 item_def_id: self.item_def_id,
1432 substs: tcx.mk_substs_trait(self_ty, self.substs),
1438 pub fn erase_self_ty(
1440 projection_predicate: ty::ProjectionPredicate<'tcx>,
1442 // Assert there is a Self.
1443 projection_predicate.projection_ty.substs.type_at(0);
1446 item_def_id: projection_predicate.projection_ty.item_def_id,
1447 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1448 term: projection_predicate.term,
1453 impl<'tcx> PolyExistentialProjection<'tcx> {
1454 pub fn with_self_ty(
1458 ) -> ty::PolyProjectionPredicate<'tcx> {
1459 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1462 pub fn item_def_id(&self) -> DefId {
1463 self.skip_binder().item_def_id
1467 /// Region utilities
1468 impl<'tcx> Region<'tcx> {
1469 pub fn kind(self) -> RegionKind<'tcx> {
1473 pub fn get_name(self) -> Option<Symbol> {
1474 if self.has_name() {
1475 let name = match *self {
1476 ty::ReEarlyBound(ebr) => Some(ebr.name),
1477 ty::ReLateBound(_, br) => br.kind.get_name(),
1478 ty::ReFree(fr) => fr.bound_region.get_name(),
1479 ty::ReStatic => Some(kw::StaticLifetime),
1480 ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
1490 /// Is this region named by the user?
1491 pub fn has_name(self) -> bool {
1493 ty::ReEarlyBound(ebr) => ebr.has_name(),
1494 ty::ReLateBound(_, br) => br.kind.is_named(),
1495 ty::ReFree(fr) => fr.bound_region.is_named(),
1496 ty::ReStatic => true,
1497 ty::ReVar(..) => false,
1498 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1499 ty::ReErased => false,
1504 pub fn is_static(self) -> bool {
1505 matches!(*self, ty::ReStatic)
1509 pub fn is_erased(self) -> bool {
1510 matches!(*self, ty::ReErased)
1514 pub fn is_late_bound(self) -> bool {
1515 matches!(*self, ty::ReLateBound(..))
1519 pub fn is_placeholder(self) -> bool {
1520 matches!(*self, ty::RePlaceholder(..))
1524 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1526 ty::ReLateBound(debruijn, _) => debruijn >= index,
1531 pub fn type_flags(self) -> TypeFlags {
1532 let mut flags = TypeFlags::empty();
1536 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1537 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1538 flags = flags | TypeFlags::HAS_RE_INFER;
1540 ty::RePlaceholder(..) => {
1541 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1542 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1543 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1545 ty::ReEarlyBound(..) => {
1546 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1547 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1548 flags = flags | TypeFlags::HAS_RE_PARAM;
1550 ty::ReFree { .. } => {
1551 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1552 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1555 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1557 ty::ReLateBound(..) => {
1558 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1561 flags = flags | TypeFlags::HAS_RE_ERASED;
1565 debug!("type_flags({:?}) = {:?}", self, flags);
1570 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1571 /// For example, consider the regions in this snippet of code:
1573 /// ```ignore (illustrative)
1575 /// // ^^ -- early bound, declared on an impl
1577 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1578 /// // ^^ ^^ ^ anonymous, late-bound
1579 /// // | early-bound, appears in where-clauses
1580 /// // late-bound, appears only in fn args
1585 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1586 /// of the impl, and for all the other highlighted regions, it
1587 /// would return the `DefId` of the function. In other cases (not shown), this
1588 /// function might return the `DefId` of a closure.
1589 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1591 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1592 ty::ReFree(fr) => fr.scope,
1593 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1597 /// True for free regions other than `'static`.
1598 pub fn is_free(self) -> bool {
1599 matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
1602 /// True if `self` is a free region or static.
1603 pub fn is_free_or_static(self) -> bool {
1605 ty::ReStatic => true,
1606 _ => self.is_free(),
1610 pub fn is_var(self) -> bool {
1611 matches!(self.kind(), ty::ReVar(_))
1616 impl<'tcx> Ty<'tcx> {
1618 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1623 pub fn flags(self) -> TypeFlags {
1628 pub fn is_unit(self) -> bool {
1630 Tuple(ref tys) => tys.is_empty(),
1636 pub fn is_never(self) -> bool {
1637 matches!(self.kind(), Never)
1641 pub fn is_primitive(self) -> bool {
1642 self.kind().is_primitive()
1646 pub fn is_adt(self) -> bool {
1647 matches!(self.kind(), Adt(..))
1651 pub fn is_ref(self) -> bool {
1652 matches!(self.kind(), Ref(..))
1656 pub fn is_ty_var(self) -> bool {
1657 matches!(self.kind(), Infer(TyVar(_)))
1661 pub fn ty_vid(self) -> Option<ty::TyVid> {
1663 &Infer(TyVar(vid)) => Some(vid),
1669 pub fn is_ty_infer(self) -> bool {
1670 matches!(self.kind(), Infer(_))
1674 pub fn is_phantom_data(self) -> bool {
1675 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1679 pub fn is_bool(self) -> bool {
1680 *self.kind() == Bool
1683 /// Returns `true` if this type is a `str`.
1685 pub fn is_str(self) -> bool {
1690 pub fn is_param(self, index: u32) -> bool {
1692 ty::Param(ref data) => data.index == index,
1698 pub fn is_slice(self) -> bool {
1699 matches!(self.kind(), Slice(_))
1703 pub fn is_array_slice(self) -> bool {
1706 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1712 pub fn is_array(self) -> bool {
1713 matches!(self.kind(), Array(..))
1717 pub fn is_simd(self) -> bool {
1719 Adt(def, _) => def.repr().simd(),
1724 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1726 Array(ty, _) | Slice(ty) => *ty,
1727 Str => tcx.types.u8,
1728 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1732 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1734 Adt(def, substs) => {
1735 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1736 let variant = def.non_enum_variant();
1737 let f0_ty = variant.fields[0].ty(tcx, substs);
1739 match f0_ty.kind() {
1740 // If the first field is an array, we assume it is the only field and its
1741 // elements are the SIMD components.
1742 Array(f0_elem_ty, f0_len) => {
1743 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1744 // The way we evaluate the `N` in `[T; N]` here only works since we use
1745 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1746 // if we use it in generic code. See the `simd-array-trait` ui test.
1747 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1749 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1750 // all have the same type).
1751 _ => (variant.fields.len() as u64, f0_ty),
1754 _ => bug!("`simd_size_and_type` called on invalid type"),
1759 pub fn is_region_ptr(self) -> bool {
1760 matches!(self.kind(), Ref(..))
1764 pub fn is_mutable_ptr(self) -> bool {
1767 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1768 | Ref(_, _, hir::Mutability::Mut)
1772 /// Get the mutability of the reference or `None` when not a reference
1774 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1776 Ref(_, _, mutability) => Some(*mutability),
1782 pub fn is_unsafe_ptr(self) -> bool {
1783 matches!(self.kind(), RawPtr(_))
1786 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1788 pub fn is_any_ptr(self) -> bool {
1789 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1793 pub fn is_box(self) -> bool {
1795 Adt(def, _) => def.is_box(),
1800 /// Panics if called on any type other than `Box<T>`.
1801 pub fn boxed_ty(self) -> Ty<'tcx> {
1803 Adt(def, substs) if def.is_box() => substs.type_at(0),
1804 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1808 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1809 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1810 /// contents are abstract to rustc.)
1812 pub fn is_scalar(self) -> bool {
1822 | Infer(IntVar(_) | FloatVar(_))
1826 /// Returns `true` if this type is a floating point type.
1828 pub fn is_floating_point(self) -> bool {
1829 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1833 pub fn is_trait(self) -> bool {
1834 matches!(self.kind(), Dynamic(_, _, ty::Dyn))
1838 pub fn is_dyn_star(self) -> bool {
1839 matches!(self.kind(), Dynamic(_, _, ty::DynStar))
1843 pub fn is_enum(self) -> bool {
1844 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1848 pub fn is_union(self) -> bool {
1849 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1853 pub fn is_closure(self) -> bool {
1854 matches!(self.kind(), Closure(..))
1858 pub fn is_generator(self) -> bool {
1859 matches!(self.kind(), Generator(..))
1863 pub fn is_integral(self) -> bool {
1864 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
1868 pub fn is_fresh_ty(self) -> bool {
1869 matches!(self.kind(), Infer(FreshTy(_)))
1873 pub fn is_fresh(self) -> bool {
1874 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
1878 pub fn is_char(self) -> bool {
1879 matches!(self.kind(), Char)
1883 pub fn is_numeric(self) -> bool {
1884 self.is_integral() || self.is_floating_point()
1888 pub fn is_signed(self) -> bool {
1889 matches!(self.kind(), Int(_))
1893 pub fn is_ptr_sized_integral(self) -> bool {
1894 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
1898 pub fn has_concrete_skeleton(self) -> bool {
1899 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
1902 /// Checks whether a type recursively contains another type
1904 /// Example: `Option<()>` contains `()`
1905 pub fn contains(self, other: Ty<'tcx>) -> bool {
1906 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
1908 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
1911 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1912 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
1916 let cf = self.visit_with(&mut ContainsTyVisitor(other));
1920 /// Returns the type and mutability of `*ty`.
1922 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1923 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1924 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1926 Adt(def, _) if def.is_box() => {
1927 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
1929 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
1930 RawPtr(mt) if explicit => Some(*mt),
1935 /// Returns the type of `ty[i]`.
1936 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
1938 Array(ty, _) | Slice(ty) => Some(*ty),
1943 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
1945 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
1948 // ignore errors (#54954)
1949 ty::Binder::dummy(FnSig::fake())
1951 Closure(..) => bug!(
1952 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1954 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
1959 pub fn is_fn(self) -> bool {
1960 matches!(self.kind(), FnDef(..) | FnPtr(_))
1964 pub fn is_fn_ptr(self) -> bool {
1965 matches!(self.kind(), FnPtr(_))
1969 pub fn is_impl_trait(self) -> bool {
1970 matches!(self.kind(), Opaque(..))
1974 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
1976 Adt(adt, _) => Some(*adt),
1981 /// Iterates over tuple fields.
1982 /// Panics when called on anything but a tuple.
1984 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
1986 Tuple(substs) => substs,
1987 _ => bug!("tuple_fields called on non-tuple"),
1991 /// If the type contains variants, returns the valid range of variant indices.
1993 // FIXME: This requires the optimized MIR in the case of generators.
1995 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
1997 TyKind::Adt(adt, _) => Some(adt.variant_range()),
1998 TyKind::Generator(def_id, substs, _) => {
1999 Some(substs.as_generator().variant_range(*def_id, tcx))
2005 /// If the type contains variants, returns the variant for `variant_index`.
2006 /// Panics if `variant_index` is out of range.
2008 // FIXME: This requires the optimized MIR in the case of generators.
2010 pub fn discriminant_for_variant(
2013 variant_index: VariantIdx,
2014 ) -> Option<Discr<'tcx>> {
2016 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2017 // This can actually happen during CTFE, see
2018 // https://github.com/rust-lang/rust/issues/89765.
2021 TyKind::Adt(adt, _) if adt.is_enum() => {
2022 Some(adt.discriminant_for_variant(tcx, variant_index))
2024 TyKind::Generator(def_id, substs, _) => {
2025 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2031 /// Returns the type of the discriminant of this type.
2032 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2034 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2035 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2037 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2038 let assoc_items = tcx.associated_item_def_ids(
2039 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2041 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2060 | ty::GeneratorWitness(..)
2064 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2067 | ty::Placeholder(_)
2068 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2069 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2074 /// Returns the type of metadata for (potentially fat) pointers to this type,
2075 /// and a boolean signifying if this is conditional on this type being `Sized`.
2076 pub fn ptr_metadata_ty(
2079 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2080 ) -> (Ty<'tcx>, bool) {
2081 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2084 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2095 | ty::GeneratorWitness(..)
2100 // Extern types have metadata = ().
2102 // If returned by `struct_tail_without_normalization` this is a unit struct
2103 // without any fields, or not a struct, and therefore is Sized.
2105 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2106 // a.k.a. unit type, which is Sized
2107 | ty::Tuple(..) => (tcx.types.unit, false),
2109 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2110 ty::Dynamic(..) => {
2111 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2112 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2115 // type parameters only have unit metadata if they're sized, so return true
2116 // to make sure we double check this during confirmation
2117 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2119 ty::Infer(ty::TyVar(_))
2121 | ty::Placeholder(..)
2122 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2123 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2128 /// When we create a closure, we record its kind (i.e., what trait
2129 /// it implements) into its `ClosureSubsts` using a type
2130 /// parameter. This is kind of a phantom type, except that the
2131 /// most convenient thing for us to are the integral types. This
2132 /// function converts such a special type into the closure
2133 /// kind. To go the other way, use
2134 /// `tcx.closure_kind_ty(closure_kind)`.
2136 /// Note that during type checking, we use an inference variable
2137 /// to represent the closure kind, because it has not yet been
2138 /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
2139 /// is complete, that type variable will be unified.
2140 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2142 Int(int_ty) => match int_ty {
2143 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2144 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2145 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2146 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2149 // "Bound" types appear in canonical queries when the
2150 // closure type is not yet known
2151 Bound(..) | Infer(_) => None,
2153 Error(_) => Some(ty::ClosureKind::Fn),
2155 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2159 /// Fast path helper for testing if a type is `Sized`.
2161 /// Returning true means the type is known to be sized. Returning
2162 /// `false` means nothing -- could be sized, might not be.
2164 /// Note that we could never rely on the fact that a type such as `[_]` is
2165 /// trivially `!Sized` because we could be in a type environment with a
2166 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2167 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2168 /// this method doesn't return `Option<bool>`.
2169 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2171 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2182 | ty::GeneratorWitness(..)
2186 | ty::Error(_) => true,
2188 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2190 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2192 ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(),
2194 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2196 ty::Infer(ty::TyVar(_)) => false,
2199 | ty::Placeholder(..)
2200 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2201 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2206 /// Fast path helper for primitives which are always `Copy` and which
2207 /// have a side-effect-free `Clone` impl.
2209 /// Returning true means the type is known to be pure and `Copy+Clone`.
2210 /// Returning `false` means nothing -- could be `Copy`, might not be.
2212 /// This is mostly useful for optimizations, as there are the types
2213 /// on which we can replace cloning with dereferencing.
2214 pub fn is_trivially_pure_clone_copy(self) -> bool {
2216 ty::Bool | ty::Char | ty::Never => true,
2218 // These aren't even `Clone`
2219 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2221 ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
2224 | ty::Float(..) => true,
2226 // The voldemort ZSTs are fine.
2227 ty::FnDef(..) => true,
2229 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2231 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2232 ty::Tuple(field_tys) => {
2233 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2236 // Sometimes traits aren't implemented for every ABI or arity,
2237 // because we can't be generic over everything yet.
2238 ty::FnPtr(..) => false,
2240 // Definitely absolutely not copy.
2241 ty::Ref(_, _, hir::Mutability::Mut) => false,
2243 // Thin pointers & thin shared references are pure-clone-copy, but for
2244 // anything with custom metadata it might be more complicated.
2245 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2247 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2249 // Might be, but not "trivial" so just giving the safe answer.
2250 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2252 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2254 ty::Bound(..) | ty::Placeholder(..) => {
2255 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2260 // If `self` is a primitive, return its [`Symbol`].
2261 pub fn primitive_symbol(self) -> Option<Symbol> {
2263 ty::Bool => Some(sym::bool),
2264 ty::Char => Some(sym::char),
2265 ty::Float(f) => match f {
2266 ty::FloatTy::F32 => Some(sym::f32),
2267 ty::FloatTy::F64 => Some(sym::f64),
2269 ty::Int(f) => match f {
2270 ty::IntTy::Isize => Some(sym::isize),
2271 ty::IntTy::I8 => Some(sym::i8),
2272 ty::IntTy::I16 => Some(sym::i16),
2273 ty::IntTy::I32 => Some(sym::i32),
2274 ty::IntTy::I64 => Some(sym::i64),
2275 ty::IntTy::I128 => Some(sym::i128),
2277 ty::Uint(f) => match f {
2278 ty::UintTy::Usize => Some(sym::usize),
2279 ty::UintTy::U8 => Some(sym::u8),
2280 ty::UintTy::U16 => Some(sym::u16),
2281 ty::UintTy::U32 => Some(sym::u32),
2282 ty::UintTy::U64 => Some(sym::u64),
2283 ty::UintTy::U128 => Some(sym::u128),
2290 /// Extra information about why we ended up with a particular variance.
2291 /// This is only used to add more information to error messages, and
2292 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2293 /// may lead to confusing notes in error messages, it will never cause
2294 /// a miscompilation or unsoundness.
2296 /// When in doubt, use `VarianceDiagInfo::default()`
2297 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2298 pub enum VarianceDiagInfo<'tcx> {
2299 /// No additional information - this is the default.
2300 /// We will not add any additional information to error messages.
2303 /// We switched our variance because a generic argument occurs inside
2304 /// the invariant generic argument of another type.
2306 /// The generic type containing the generic parameter
2307 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2309 /// The index of the generic parameter being used
2310 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2315 impl<'tcx> VarianceDiagInfo<'tcx> {
2316 /// Mirrors `Variance::xform` - used to 'combine' the existing
2317 /// and new `VarianceDiagInfo`s when our variance changes.
2318 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2319 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2321 VarianceDiagInfo::None => other,
2322 VarianceDiagInfo::Invariant { .. } => self,