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_hir::LangItem;
21 use rustc_index::vec::Idx;
22 use rustc_macros::HashStable;
23 use rustc_span::symbol::{kw, sym, Symbol};
25 use rustc_target::abi::VariantIdx;
26 use rustc_target::spec::abi;
28 use std::cmp::Ordering;
30 use std::marker::PhantomData;
31 use std::ops::{ControlFlow, Deref, Range};
32 use ty::util::IntTypeExt;
34 use rustc_type_ir::sty::TyKind::*;
35 use rustc_type_ir::RegionKind as IrRegionKind;
36 use rustc_type_ir::TyKind as IrTyKind;
38 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
39 #[rustc_diagnostic_item = "TyKind"]
40 pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
41 pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
43 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
44 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
45 pub struct TypeAndMut<'tcx> {
47 pub mutbl: hir::Mutability,
50 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
52 /// A "free" region `fr` can be interpreted as "some region
53 /// at least as big as the scope `fr.scope`".
54 pub struct FreeRegion {
56 pub bound_region: BoundRegionKind,
59 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
61 pub enum BoundRegionKind {
62 /// An anonymous region parameter for a given fn (&T)
63 BrAnon(u32, Option<Span>),
65 /// Named region parameters for functions (a in &'a T)
67 /// The `DefId` is needed to distinguish free regions in
68 /// the event of shadowing.
69 BrNamed(DefId, Symbol),
71 /// Anonymous region for the implicit env pointer parameter
76 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
78 pub struct BoundRegion {
80 pub kind: BoundRegionKind,
83 impl BoundRegionKind {
84 pub fn is_named(&self) -> bool {
86 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
91 pub fn get_name(&self) -> Option<Symbol> {
94 BoundRegionKind::BrNamed(_, name) => return Some(name),
104 fn article(&self) -> &'static str;
107 impl<'tcx> Article for TyKind<'tcx> {
108 /// Get the article ("a" or "an") to use with this type.
109 fn article(&self) -> &'static str {
111 Int(_) | Float(_) | Array(_, _) => "an",
112 Adt(def, _) if def.is_enum() => "an",
113 // This should never happen, but ICEing and causing the user's code
114 // to not compile felt too harsh.
121 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
122 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
123 static_assert_size!(TyKind<'_>, 32);
125 /// A closure can be modeled as a struct that looks like:
126 /// ```ignore (illustrative)
127 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
131 /// - 'l0...'li and T0...Tj are the generic parameters
132 /// in scope on the function that defined the closure,
133 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
134 /// is rather hackily encoded via a scalar type. See
135 /// `Ty::to_opt_closure_kind` for details.
136 /// - CS represents the *closure signature*, representing as a `fn()`
137 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
138 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
140 /// - U is a type parameter representing the types of its upvars, tupled up
141 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
142 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
144 /// So, for example, given this function:
145 /// ```ignore (illustrative)
146 /// fn foo<'a, T>(data: &'a mut T) {
147 /// do(|| data.count += 1)
150 /// the type of the closure would be something like:
151 /// ```ignore (illustrative)
152 /// struct Closure<'a, T, U>(...U);
154 /// Note that the type of the upvar is not specified in the struct.
155 /// You may wonder how the impl would then be able to use the upvar,
156 /// if it doesn't know it's type? The answer is that the impl is
157 /// (conceptually) not fully generic over Closure but rather tied to
158 /// instances with the expected upvar types:
159 /// ```ignore (illustrative)
160 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
164 /// You can see that the *impl* fully specified the type of the upvar
165 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
166 /// (Here, I am assuming that `data` is mut-borrowed.)
168 /// Now, the last question you may ask is: Why include the upvar types
169 /// in an extra type parameter? The reason for this design is that the
170 /// upvar types can reference lifetimes that are internal to the
171 /// creating function. In my example above, for example, the lifetime
172 /// `'b` represents the scope of the closure itself; this is some
173 /// subset of `foo`, probably just the scope of the call to the to
174 /// `do()`. If we just had the lifetime/type parameters from the
175 /// enclosing function, we couldn't name this lifetime `'b`. Note that
176 /// there can also be lifetimes in the types of the upvars themselves,
177 /// if one of them happens to be a reference to something that the
178 /// creating fn owns.
180 /// OK, you say, so why not create a more minimal set of parameters
181 /// that just includes the extra lifetime parameters? The answer is
182 /// primarily that it would be hard --- we don't know at the time when
183 /// we create the closure type what the full types of the upvars are,
184 /// nor do we know which are borrowed and which are not. In this
185 /// design, we can just supply a fresh type parameter and figure that
188 /// All right, you say, but why include the type parameters from the
189 /// original function then? The answer is that codegen may need them
190 /// when monomorphizing, and they may not appear in the upvars. A
191 /// closure could capture no variables but still make use of some
192 /// in-scope type parameter with a bound (e.g., if our example above
193 /// had an extra `U: Default`, and the closure called `U::default()`).
195 /// There is another reason. This design (implicitly) prohibits
196 /// closures from capturing themselves (except via a trait
197 /// object). This simplifies closure inference considerably, since it
198 /// means that when we infer the kind of a closure or its upvars, we
199 /// don't have to handle cycles where the decisions we make for
200 /// closure C wind up influencing the decisions we ought to make for
201 /// closure C (which would then require fixed point iteration to
202 /// handle). Plus it fixes an ICE. :P
206 /// Generators are handled similarly in `GeneratorSubsts`. The set of
207 /// type parameters is similar, but `CK` and `CS` are replaced by the
208 /// following type parameters:
210 /// * `GS`: The generator's "resume type", which is the type of the
211 /// argument passed to `resume`, and the type of `yield` expressions
212 /// inside the generator.
213 /// * `GY`: The "yield type", which is the type of values passed to
214 /// `yield` inside the generator.
215 /// * `GR`: The "return type", which is the type of value returned upon
216 /// completion of the generator.
217 /// * `GW`: The "generator witness".
218 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
219 pub struct ClosureSubsts<'tcx> {
220 /// Lifetime and type parameters from the enclosing function,
221 /// concatenated with a tuple containing the types of the upvars.
223 /// These are separated out because codegen wants to pass them around
224 /// when monomorphizing.
225 pub substs: SubstsRef<'tcx>,
228 /// Struct returned by `split()`.
229 pub struct ClosureSubstsParts<'tcx, T> {
230 pub parent_substs: &'tcx [GenericArg<'tcx>],
231 pub closure_kind_ty: T,
232 pub closure_sig_as_fn_ptr_ty: T,
233 pub tupled_upvars_ty: T,
236 impl<'tcx> ClosureSubsts<'tcx> {
237 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
238 /// for the closure parent, alongside additional closure-specific components.
241 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
242 ) -> ClosureSubsts<'tcx> {
244 substs: tcx.mk_substs(
245 parts.parent_substs.iter().copied().chain(
246 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
248 .map(|&ty| ty.into()),
254 /// Divides the closure substs into their respective components.
255 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
256 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
257 match self.substs[..] {
259 ref parent_substs @ ..,
261 closure_sig_as_fn_ptr_ty,
263 ] => ClosureSubstsParts {
266 closure_sig_as_fn_ptr_ty,
269 _ => bug!("closure substs missing synthetics"),
273 /// Returns `true` only if enough of the synthetic types are known to
274 /// allow using all of the methods on `ClosureSubsts` without panicking.
276 /// Used primarily by `ty::print::pretty` to be able to handle closure
277 /// types that haven't had their synthetic types substituted in.
278 pub fn is_valid(self) -> bool {
279 self.substs.len() >= 3
280 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
283 /// Returns the substitutions of the closure's parent.
284 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
285 self.split().parent_substs
288 /// Returns an iterator over the list of types of captured paths by the closure.
289 /// In case there was a type error in figuring out the types of the captured path, an
290 /// empty iterator is returned.
292 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
293 match self.tupled_upvars_ty().kind() {
294 TyKind::Error(_) => None,
295 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
296 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
297 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
303 /// Returns the tuple type representing the upvars for this closure.
305 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
306 self.split().tupled_upvars_ty.expect_ty()
309 /// Returns the closure kind for this closure; may return a type
310 /// variable during inference. To get the closure kind during
311 /// inference, use `infcx.closure_kind(substs)`.
312 pub fn kind_ty(self) -> Ty<'tcx> {
313 self.split().closure_kind_ty.expect_ty()
316 /// Returns the `fn` pointer type representing the closure signature for this
318 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
319 // type is known at the time of the creation of `ClosureSubsts`,
320 // see `rustc_hir_analysis::check::closure`.
321 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
322 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
325 /// Returns the closure kind for this closure; only usable outside
326 /// of an inference context, because in that context we know that
327 /// there are no type variables.
329 /// If you have an inference context, use `infcx.closure_kind()`.
330 pub fn kind(self) -> ty::ClosureKind {
331 self.kind_ty().to_opt_closure_kind().unwrap()
334 /// Extracts the signature from the closure.
335 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
336 let ty = self.sig_as_fn_ptr_ty();
338 ty::FnPtr(sig) => *sig,
339 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
343 pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
344 ty::print::PrintClosureAsImpl { closure: self }
348 /// Similar to `ClosureSubsts`; see the above documentation for more.
349 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
350 pub struct GeneratorSubsts<'tcx> {
351 pub substs: SubstsRef<'tcx>,
354 pub struct GeneratorSubstsParts<'tcx, T> {
355 pub parent_substs: &'tcx [GenericArg<'tcx>],
360 pub tupled_upvars_ty: T,
363 impl<'tcx> GeneratorSubsts<'tcx> {
364 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
365 /// for the generator parent, alongside additional generator-specific components.
368 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
369 ) -> GeneratorSubsts<'tcx> {
371 substs: tcx.mk_substs(
372 parts.parent_substs.iter().copied().chain(
378 parts.tupled_upvars_ty,
381 .map(|&ty| ty.into()),
387 /// Divides the generator substs into their respective components.
388 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
389 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
390 match self.substs[..] {
391 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
392 GeneratorSubstsParts {
401 _ => bug!("generator substs missing synthetics"),
405 /// Returns `true` only if enough of the synthetic types are known to
406 /// allow using all of the methods on `GeneratorSubsts` without panicking.
408 /// Used primarily by `ty::print::pretty` to be able to handle generator
409 /// types that haven't had their synthetic types substituted in.
410 pub fn is_valid(self) -> bool {
411 self.substs.len() >= 5
412 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
415 /// Returns the substitutions of the generator's parent.
416 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
417 self.split().parent_substs
420 /// This describes the types that can be contained in a generator.
421 /// It will be a type variable initially and unified in the last stages of typeck of a body.
422 /// It contains a tuple of all the types that could end up on a generator frame.
423 /// The state transformation MIR pass may only produce layouts which mention types
424 /// in this tuple. Upvars are not counted here.
425 pub fn witness(self) -> Ty<'tcx> {
426 self.split().witness.expect_ty()
429 /// Returns an iterator over the list of types of captured paths by the generator.
430 /// In case there was a type error in figuring out the types of the captured path, an
431 /// empty iterator is returned.
433 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
434 match self.tupled_upvars_ty().kind() {
435 TyKind::Error(_) => None,
436 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
437 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
438 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
444 /// Returns the tuple type representing the upvars for this generator.
446 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
447 self.split().tupled_upvars_ty.expect_ty()
450 /// Returns the type representing the resume type of the generator.
451 pub fn resume_ty(self) -> Ty<'tcx> {
452 self.split().resume_ty.expect_ty()
455 /// Returns the type representing the yield type of the generator.
456 pub fn yield_ty(self) -> Ty<'tcx> {
457 self.split().yield_ty.expect_ty()
460 /// Returns the type representing the return type of the generator.
461 pub fn return_ty(self) -> Ty<'tcx> {
462 self.split().return_ty.expect_ty()
465 /// Returns the "generator signature", which consists of its yield
466 /// and return types.
468 /// N.B., some bits of the code prefers to see this wrapped in a
469 /// binder, but it never contains bound regions. Probably this
470 /// function should be removed.
471 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
472 ty::Binder::dummy(self.sig())
475 /// Returns the "generator signature", which consists of its resume, yield
476 /// and return types.
477 pub fn sig(self) -> GenSig<'tcx> {
479 resume_ty: self.resume_ty(),
480 yield_ty: self.yield_ty(),
481 return_ty: self.return_ty(),
486 impl<'tcx> GeneratorSubsts<'tcx> {
487 /// Generator has not been resumed yet.
488 pub const UNRESUMED: usize = 0;
489 /// Generator has returned or is completed.
490 pub const RETURNED: usize = 1;
491 /// Generator has been poisoned.
492 pub const POISONED: usize = 2;
494 const UNRESUMED_NAME: &'static str = "Unresumed";
495 const RETURNED_NAME: &'static str = "Returned";
496 const POISONED_NAME: &'static str = "Panicked";
498 /// The valid variant indices of this generator.
500 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
501 // FIXME requires optimized MIR
502 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
503 VariantIdx::new(0)..VariantIdx::new(num_variants)
506 /// The discriminant for the given variant. Panics if the `variant_index` is
509 pub fn discriminant_for_variant(
513 variant_index: VariantIdx,
515 // Generators don't support explicit discriminant values, so they are
516 // the same as the variant index.
517 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
518 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
521 /// The set of all discriminants for the generator, enumerated with their
524 pub fn discriminants(
528 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
529 self.variant_range(def_id, tcx).map(move |index| {
530 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
534 /// Calls `f` with a reference to the name of the enumerator for the given
536 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
538 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
539 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
540 Self::POISONED => Cow::from(Self::POISONED_NAME),
541 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
545 /// The type of the state discriminant used in the generator type.
547 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
551 /// This returns the types of the MIR locals which had to be stored across suspension points.
552 /// It is calculated in rustc_mir_transform::generator::StateTransform.
553 /// All the types here must be in the tuple in GeneratorInterior.
555 /// The locals are grouped by their variant number. Note that some locals may
556 /// be repeated in multiple variants.
562 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
563 let layout = tcx.generator_layout(def_id).unwrap();
564 layout.variant_fields.iter().map(move |variant| {
567 .map(move |field| ty::EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
571 /// This is the types of the fields of a generator which are not stored in a
574 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
579 #[derive(Debug, Copy, Clone, HashStable)]
580 pub enum UpvarSubsts<'tcx> {
581 Closure(SubstsRef<'tcx>),
582 Generator(SubstsRef<'tcx>),
585 impl<'tcx> UpvarSubsts<'tcx> {
586 /// Returns an iterator over the list of types of captured paths by the closure/generator.
587 /// In case there was a type error in figuring out the types of the captured path, an
588 /// empty iterator is returned.
590 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
591 let tupled_tys = match self {
592 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
593 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
596 match tupled_tys.kind() {
597 TyKind::Error(_) => None,
598 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
599 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
600 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
607 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
609 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
610 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
615 /// An inline const is modeled like
616 /// ```ignore (illustrative)
617 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
621 /// - 'l0...'li and T0...Tj are the generic parameters
622 /// inherited from the item that defined the inline const,
623 /// - R represents the type of the constant.
625 /// When the inline const is instantiated, `R` is substituted as the actual inferred
626 /// type of the constant. The reason that `R` is represented as an extra type parameter
627 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
628 /// inline const can reference lifetimes that are internal to the creating function.
629 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
630 pub struct InlineConstSubsts<'tcx> {
631 /// Generic parameters from the enclosing item,
632 /// concatenated with the inferred type of the constant.
633 pub substs: SubstsRef<'tcx>,
636 /// Struct returned by `split()`.
637 pub struct InlineConstSubstsParts<'tcx, T> {
638 pub parent_substs: &'tcx [GenericArg<'tcx>],
642 impl<'tcx> InlineConstSubsts<'tcx> {
643 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
646 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
647 ) -> InlineConstSubsts<'tcx> {
649 substs: tcx.mk_substs(
650 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
655 /// Divides the inline const substs into their respective components.
656 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
657 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
658 match self.substs[..] {
659 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
660 _ => bug!("inline const substs missing synthetics"),
664 /// Returns the substitutions of the inline const's parent.
665 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
666 self.split().parent_substs
669 /// Returns the type of this inline const.
670 pub fn ty(self) -> Ty<'tcx> {
671 self.split().ty.expect_ty()
675 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
676 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
677 pub enum ExistentialPredicate<'tcx> {
678 /// E.g., `Iterator`.
679 Trait(ExistentialTraitRef<'tcx>),
680 /// E.g., `Iterator::Item = T`.
681 Projection(ExistentialProjection<'tcx>),
686 impl<'tcx> ExistentialPredicate<'tcx> {
687 /// Compares via an ordering that will not change if modules are reordered or other changes are
688 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
689 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
690 use self::ExistentialPredicate::*;
691 match (*self, *other) {
692 (Trait(_), Trait(_)) => Ordering::Equal,
693 (Projection(ref a), Projection(ref b)) => {
694 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
696 (AutoTrait(ref a), AutoTrait(ref b)) => {
697 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
699 (Trait(_), _) => Ordering::Less,
700 (Projection(_), Trait(_)) => Ordering::Greater,
701 (Projection(_), _) => Ordering::Less,
702 (AutoTrait(_), _) => Ordering::Greater,
707 pub type PolyExistentialPredicate<'tcx> = Binder<'tcx, ExistentialPredicate<'tcx>>;
709 impl<'tcx> PolyExistentialPredicate<'tcx> {
710 /// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
711 /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
712 /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
713 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
714 use crate::ty::ToPredicate;
715 match self.skip_binder() {
716 ExistentialPredicate::Trait(tr) => {
717 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
719 ExistentialPredicate::Projection(p) => {
720 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
722 ExistentialPredicate::AutoTrait(did) => {
723 let trait_ref = self.rebind(tcx.mk_trait_ref(did, [self_ty]));
724 trait_ref.without_const().to_predicate(tcx)
730 impl<'tcx> List<ty::PolyExistentialPredicate<'tcx>> {
731 /// Returns the "principal `DefId`" of this set of existential predicates.
733 /// A Rust trait object type consists (in addition to a lifetime bound)
734 /// of a set of trait bounds, which are separated into any number
735 /// of auto-trait bounds, and at most one non-auto-trait bound. The
736 /// non-auto-trait bound is called the "principal" of the trait
739 /// Only the principal can have methods or type parameters (because
740 /// auto traits can have neither of them). This is important, because
741 /// it means the auto traits can be treated as an unordered set (methods
742 /// would force an order for the vtable, while relating traits with
743 /// type parameters without knowing the order to relate them in is
744 /// a rather non-trivial task).
746 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
747 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
748 /// are the set `{Sync}`.
750 /// It is also possible to have a "trivial" trait object that
751 /// consists only of auto traits, with no principal - for example,
752 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
753 /// is `{Send, Sync}`, while there is no principal. These trait objects
754 /// have a "trivial" vtable consisting of just the size, alignment,
756 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
758 .map_bound(|this| match this {
759 ExistentialPredicate::Trait(tr) => Some(tr),
765 pub fn principal_def_id(&self) -> Option<DefId> {
766 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
770 pub fn projection_bounds<'a>(
772 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
773 self.iter().filter_map(|predicate| {
775 .map_bound(|pred| match pred {
776 ExistentialPredicate::Projection(projection) => Some(projection),
784 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'a {
785 self.iter().filter_map(|predicate| match predicate.skip_binder() {
786 ExistentialPredicate::AutoTrait(did) => Some(did),
792 /// A complete reference to a trait. These take numerous guises in syntax,
793 /// but perhaps the most recognizable form is in a where-clause:
794 /// ```ignore (illustrative)
797 /// This would be represented by a trait-reference where the `DefId` is the
798 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
799 /// and `U` as parameter 1.
801 /// Trait references also appear in object types like `Foo<U>`, but in
802 /// that case the `Self` parameter is absent from the substitutions.
803 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
804 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
805 pub struct TraitRef<'tcx> {
807 pub substs: SubstsRef<'tcx>,
810 impl<'tcx> TraitRef<'tcx> {
811 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
812 TraitRef { def_id, substs }
815 pub fn with_self_type(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
818 [self_ty.into()].into_iter().chain(self.substs.iter().skip(1)),
822 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
823 /// are the parameters defined on trait.
824 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
825 ty::Binder::dummy(TraitRef {
827 substs: InternalSubsts::identity_for_item(tcx, def_id),
832 pub fn self_ty(&self) -> Ty<'tcx> {
833 self.substs.type_at(0)
839 substs: SubstsRef<'tcx>,
840 ) -> ty::TraitRef<'tcx> {
841 let defs = tcx.generics_of(trait_id);
842 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
846 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
848 impl<'tcx> PolyTraitRef<'tcx> {
849 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
850 self.map_bound_ref(|tr| tr.self_ty())
853 pub fn def_id(&self) -> DefId {
854 self.skip_binder().def_id
857 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
858 self.map_bound(|trait_ref| ty::TraitPredicate {
860 constness: ty::BoundConstness::NotConst,
861 polarity: ty::ImplPolarity::Positive,
865 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
866 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
867 self.map_bound(|trait_ref| ty::TraitPredicate {
869 constness: ty::BoundConstness::NotConst,
870 polarity: ty::ImplPolarity::Negative,
875 impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
876 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
877 self.to_string().into_diagnostic_arg()
881 /// An existential reference to a trait, where `Self` is erased.
882 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
883 /// ```ignore (illustrative)
884 /// exists T. T: Trait<'a, 'b, X, Y>
886 /// The substitutions don't include the erased `Self`, only trait
887 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
888 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
889 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
890 pub struct ExistentialTraitRef<'tcx> {
892 pub substs: SubstsRef<'tcx>,
895 impl<'tcx> ExistentialTraitRef<'tcx> {
896 pub fn erase_self_ty(
898 trait_ref: ty::TraitRef<'tcx>,
899 ) -> ty::ExistentialTraitRef<'tcx> {
900 // Assert there is a Self.
901 trait_ref.substs.type_at(0);
903 ty::ExistentialTraitRef {
904 def_id: trait_ref.def_id,
905 substs: tcx.intern_substs(&trait_ref.substs[1..]),
909 /// Object types don't have a self type specified. Therefore, when
910 /// we convert the principal trait-ref into a normal trait-ref,
911 /// you must give *some* self type. A common choice is `mk_err()`
912 /// or some placeholder type.
913 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
914 // otherwise the escaping vars would be captured by the binder
915 // debug_assert!(!self_ty.has_escaping_bound_vars());
917 tcx.mk_trait_ref(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter()))
921 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
923 impl<'tcx> PolyExistentialTraitRef<'tcx> {
924 pub fn def_id(&self) -> DefId {
925 self.skip_binder().def_id
928 /// Object types don't have a self type specified. Therefore, when
929 /// we convert the principal trait-ref into a normal trait-ref,
930 /// you must give *some* self type. A common choice is `mk_err()`
931 /// or some placeholder type.
932 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
933 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
937 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
938 #[derive(HashStable)]
939 pub enum BoundVariableKind {
941 Region(BoundRegionKind),
945 impl BoundVariableKind {
946 pub fn expect_region(self) -> BoundRegionKind {
948 BoundVariableKind::Region(lt) => lt,
949 _ => bug!("expected a region, but found another kind"),
953 pub fn expect_ty(self) -> BoundTyKind {
955 BoundVariableKind::Ty(ty) => ty,
956 _ => bug!("expected a type, but found another kind"),
960 pub fn expect_const(self) {
962 BoundVariableKind::Const => (),
963 _ => bug!("expected a const, but found another kind"),
968 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
969 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
970 /// (which would be represented by the type `PolyTraitRef ==
971 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
972 /// erase, or otherwise "discharge" these bound vars, we change the
973 /// type from `Binder<'tcx, T>` to just `T` (see
974 /// e.g., `liberate_late_bound_regions`).
976 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
977 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
978 #[derive(HashStable, Lift)]
979 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
981 impl<'tcx, T> Binder<'tcx, T>
983 T: TypeVisitable<'tcx>,
985 /// Wraps `value` in a binder, asserting that `value` does not
986 /// contain any bound vars that would be bound by the
987 /// binder. This is commonly used to 'inject' a value T into a
988 /// different binding level.
989 pub fn dummy(value: T) -> Binder<'tcx, T> {
990 assert!(!value.has_escaping_bound_vars());
991 Binder(value, ty::List::empty())
994 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
995 if cfg!(debug_assertions) {
996 let mut validator = ValidateBoundVars::new(vars);
997 value.visit_with(&mut validator);
1003 impl<'tcx, T> Binder<'tcx, T> {
1004 /// Skips the binder and returns the "bound" value. This is a
1005 /// risky thing to do because it's easy to get confused about
1006 /// De Bruijn indices and the like. It is usually better to
1007 /// discharge the binder using `no_bound_vars` or
1008 /// `replace_late_bound_regions` or something like
1009 /// that. `skip_binder` is only valid when you are either
1010 /// extracting data that has nothing to do with bound vars, you
1011 /// are doing some sort of test that does not involve bound
1012 /// regions, or you are being very careful about your depth
1015 /// Some examples where `skip_binder` is reasonable:
1017 /// - extracting the `DefId` from a PolyTraitRef;
1018 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1019 /// a type parameter `X`, since the type `X` does not reference any regions
1020 pub fn skip_binder(self) -> T {
1024 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1028 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1029 Binder(&self.0, self.1)
1032 pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
1036 Binder(&self.0, self.1)
1039 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1043 let value = f(&self.0);
1044 Binder(value, self.1)
1047 pub fn map_bound_ref<F, U: TypeVisitable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1051 self.as_ref().map_bound(f)
1054 pub fn map_bound<F, U: TypeVisitable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1058 let value = f(self.0);
1059 if cfg!(debug_assertions) {
1060 let mut validator = ValidateBoundVars::new(self.1);
1061 value.visit_with(&mut validator);
1063 Binder(value, self.1)
1066 pub fn try_map_bound<F, U: TypeVisitable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1068 F: FnOnce(T) -> Result<U, E>,
1070 let value = f(self.0)?;
1071 if cfg!(debug_assertions) {
1072 let mut validator = ValidateBoundVars::new(self.1);
1073 value.visit_with(&mut validator);
1075 Ok(Binder(value, self.1))
1078 /// Wraps a `value` in a binder, using the same bound variables as the
1079 /// current `Binder`. This should not be used if the new value *changes*
1080 /// the bound variables. Note: the (old or new) value itself does not
1081 /// necessarily need to *name* all the bound variables.
1083 /// This currently doesn't do anything different than `bind`, because we
1084 /// don't actually track bound vars. However, semantically, it is different
1085 /// because bound vars aren't allowed to change here, whereas they are
1086 /// in `bind`. This may be (debug) asserted in the future.
1087 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1089 U: TypeVisitable<'tcx>,
1091 if cfg!(debug_assertions) {
1092 let mut validator = ValidateBoundVars::new(self.bound_vars());
1093 value.visit_with(&mut validator);
1095 Binder(value, self.1)
1098 /// Unwraps and returns the value within, but only if it contains
1099 /// no bound vars at all. (In other words, if this binder --
1100 /// and indeed any enclosing binder -- doesn't bind anything at
1101 /// all.) Otherwise, returns `None`.
1103 /// (One could imagine having a method that just unwraps a single
1104 /// binder, but permits late-bound vars bound by enclosing
1105 /// binders, but that would require adjusting the debruijn
1106 /// indices, and given the shallow binding structure we often use,
1107 /// would not be that useful.)
1108 pub fn no_bound_vars(self) -> Option<T>
1110 T: TypeVisitable<'tcx>,
1112 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1115 /// Splits the contents into two things that share the same binder
1116 /// level as the original, returning two distinct binders.
1118 /// `f` should consider bound regions at depth 1 to be free, and
1119 /// anything it produces with bound regions at depth 1 will be
1120 /// bound in the resulting return values.
1121 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1123 F: FnOnce(T) -> (U, V),
1125 let (u, v) = f(self.0);
1126 (Binder(u, self.1), Binder(v, self.1))
1130 impl<'tcx, T> Binder<'tcx, Option<T>> {
1131 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1132 let bound_vars = self.1;
1133 self.0.map(|v| Binder(v, bound_vars))
1137 /// Represents the projection of an associated type. In explicit UFCS
1138 /// form this would be written `<T as Trait<..>>::N`.
1139 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1140 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1141 pub struct ProjectionTy<'tcx> {
1142 /// The parameters of the associated item.
1143 pub substs: SubstsRef<'tcx>,
1145 /// The `DefId` of the `TraitItem` for the associated type `N`.
1147 /// Note that this is not the `DefId` of the `TraitRef` containing this
1148 /// associated type, which is in `tcx.associated_item(item_def_id).container`,
1149 /// aka. `tcx.parent(item_def_id).unwrap()`.
1150 pub item_def_id: DefId,
1153 impl<'tcx> ProjectionTy<'tcx> {
1154 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1155 match tcx.def_kind(self.item_def_id) {
1156 DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.item_def_id),
1157 DefKind::ImplTraitPlaceholder => {
1158 tcx.parent(tcx.impl_trait_in_trait_parent(self.item_def_id))
1160 kind => bug!("unexpected DefKind in ProjectionTy: {kind:?}"),
1164 /// Extracts the underlying trait reference and own substs from this projection.
1165 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1166 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1167 pub fn trait_ref_and_own_substs(
1170 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1171 let def_id = tcx.parent(self.item_def_id);
1172 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
1173 let trait_generics = tcx.generics_of(def_id);
1175 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1176 &self.substs[trait_generics.count()..],
1180 /// Extracts the underlying trait reference from this projection.
1181 /// For example, if this is a projection of `<T as Iterator>::Item`,
1182 /// then this function would return a `T: Iterator` trait reference.
1184 /// WARNING: This will drop the substs for generic associated types
1185 /// consider calling [Self::trait_ref_and_own_substs] to get those
1187 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1188 let def_id = self.trait_def_id(tcx);
1189 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1192 pub fn self_ty(&self) -> Ty<'tcx> {
1193 self.substs.type_at(0)
1197 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
1198 pub struct GenSig<'tcx> {
1199 pub resume_ty: Ty<'tcx>,
1200 pub yield_ty: Ty<'tcx>,
1201 pub return_ty: Ty<'tcx>,
1204 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1206 /// Signature of a function type, which we have arbitrarily
1207 /// decided to use to refer to the input/output types.
1209 /// - `inputs`: is the list of arguments and their modes.
1210 /// - `output`: is the return type.
1211 /// - `c_variadic`: indicates whether this is a C-variadic function.
1212 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1213 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1214 pub struct FnSig<'tcx> {
1215 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1216 pub c_variadic: bool,
1217 pub unsafety: hir::Unsafety,
1221 impl<'tcx> FnSig<'tcx> {
1222 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1223 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1226 pub fn output(&self) -> Ty<'tcx> {
1227 self.inputs_and_output[self.inputs_and_output.len() - 1]
1230 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1232 fn fake() -> FnSig<'tcx> {
1234 inputs_and_output: List::empty(),
1236 unsafety: hir::Unsafety::Normal,
1237 abi: abi::Abi::Rust,
1242 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1244 impl<'tcx> PolyFnSig<'tcx> {
1246 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1247 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1250 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1251 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1253 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1254 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1257 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1258 self.map_bound_ref(|fn_sig| fn_sig.output())
1260 pub fn c_variadic(&self) -> bool {
1261 self.skip_binder().c_variadic
1263 pub fn unsafety(&self) -> hir::Unsafety {
1264 self.skip_binder().unsafety
1266 pub fn abi(&self) -> abi::Abi {
1267 self.skip_binder().abi
1271 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1273 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1274 #[derive(HashStable)]
1275 pub struct ParamTy {
1280 impl<'tcx> ParamTy {
1281 pub fn new(index: u32, name: Symbol) -> ParamTy {
1282 ParamTy { index, name }
1285 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1286 ParamTy::new(def.index, def.name)
1290 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1291 tcx.mk_ty_param(self.index, self.name)
1294 pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
1295 let generics = tcx.generics_of(item_with_generics);
1296 let type_param = generics.type_param(self, tcx);
1297 tcx.def_span(type_param.def_id)
1301 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1302 #[derive(HashStable)]
1303 pub struct ParamConst {
1309 pub fn new(index: u32, name: Symbol) -> ParamConst {
1310 ParamConst { index, name }
1313 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1314 ParamConst::new(def.index, def.name)
1318 /// Use this rather than `RegionKind`, whenever possible.
1319 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1320 #[rustc_pass_by_value]
1321 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
1323 impl<'tcx> Deref for Region<'tcx> {
1324 type Target = RegionKind<'tcx>;
1327 fn deref(&self) -> &RegionKind<'tcx> {
1332 impl<'tcx> fmt::Debug for Region<'tcx> {
1333 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1334 write!(f, "{:?}", self.kind())
1338 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1339 #[derive(HashStable)]
1340 pub struct EarlyBoundRegion {
1346 impl fmt::Debug for EarlyBoundRegion {
1347 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1348 write!(f, "{}, {}", self.index, self.name)
1352 /// A **`const`** **v**ariable **ID**.
1353 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1354 #[derive(HashStable, TyEncodable, TyDecodable)]
1355 pub struct ConstVid<'tcx> {
1357 pub phantom: PhantomData<&'tcx ()>,
1360 rustc_index::newtype_index! {
1361 /// A **region** (lifetime) **v**ariable **ID**.
1362 #[derive(HashStable)]
1363 pub struct RegionVid {
1364 DEBUG_FORMAT = custom,
1368 impl Atom for RegionVid {
1369 fn index(self) -> usize {
1374 rustc_index::newtype_index! {
1375 #[derive(HashStable)]
1376 pub struct BoundVar { .. }
1379 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1380 #[derive(HashStable)]
1381 pub struct BoundTy {
1383 pub kind: BoundTyKind,
1386 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1387 #[derive(HashStable)]
1388 pub enum BoundTyKind {
1393 impl From<BoundVar> for BoundTy {
1394 fn from(var: BoundVar) -> Self {
1395 BoundTy { var, kind: BoundTyKind::Anon }
1399 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1400 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1401 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1402 pub struct ExistentialProjection<'tcx> {
1403 pub item_def_id: DefId,
1404 pub substs: SubstsRef<'tcx>,
1405 pub term: Term<'tcx>,
1408 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1410 impl<'tcx> ExistentialProjection<'tcx> {
1411 /// Extracts the underlying existential trait reference from this projection.
1412 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1413 /// then this function would return an `exists T. T: Iterator` existential trait
1415 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1416 let def_id = tcx.parent(self.item_def_id);
1417 let subst_count = tcx.generics_of(def_id).count() - 1;
1418 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1419 ty::ExistentialTraitRef { def_id, substs }
1422 pub fn with_self_ty(
1426 ) -> ty::ProjectionPredicate<'tcx> {
1427 // otherwise the escaping regions would be captured by the binders
1428 debug_assert!(!self_ty.has_escaping_bound_vars());
1430 ty::ProjectionPredicate {
1431 projection_ty: ty::ProjectionTy {
1432 item_def_id: self.item_def_id,
1433 substs: tcx.mk_substs_trait(self_ty, self.substs),
1439 pub fn erase_self_ty(
1441 projection_predicate: ty::ProjectionPredicate<'tcx>,
1443 // Assert there is a Self.
1444 projection_predicate.projection_ty.substs.type_at(0);
1447 item_def_id: projection_predicate.projection_ty.item_def_id,
1448 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1449 term: projection_predicate.term,
1454 impl<'tcx> PolyExistentialProjection<'tcx> {
1455 pub fn with_self_ty(
1459 ) -> ty::PolyProjectionPredicate<'tcx> {
1460 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1463 pub fn item_def_id(&self) -> DefId {
1464 self.skip_binder().item_def_id
1468 /// Region utilities
1469 impl<'tcx> Region<'tcx> {
1470 pub fn kind(self) -> RegionKind<'tcx> {
1474 pub fn get_name(self) -> Option<Symbol> {
1475 if self.has_name() {
1476 let name = match *self {
1477 ty::ReEarlyBound(ebr) => Some(ebr.name),
1478 ty::ReLateBound(_, br) => br.kind.get_name(),
1479 ty::ReFree(fr) => fr.bound_region.get_name(),
1480 ty::ReStatic => Some(kw::StaticLifetime),
1481 ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
1491 /// Is this region named by the user?
1492 pub fn has_name(self) -> bool {
1494 ty::ReEarlyBound(ebr) => ebr.has_name(),
1495 ty::ReLateBound(_, br) => br.kind.is_named(),
1496 ty::ReFree(fr) => fr.bound_region.is_named(),
1497 ty::ReStatic => true,
1498 ty::ReVar(..) => false,
1499 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1500 ty::ReErased => false,
1505 pub fn is_static(self) -> bool {
1506 matches!(*self, ty::ReStatic)
1510 pub fn is_erased(self) -> bool {
1511 matches!(*self, ty::ReErased)
1515 pub fn is_late_bound(self) -> bool {
1516 matches!(*self, ty::ReLateBound(..))
1520 pub fn is_placeholder(self) -> bool {
1521 matches!(*self, ty::RePlaceholder(..))
1525 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1527 ty::ReLateBound(debruijn, _) => debruijn >= index,
1532 pub fn type_flags(self) -> TypeFlags {
1533 let mut flags = TypeFlags::empty();
1537 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1538 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1539 flags = flags | TypeFlags::HAS_RE_INFER;
1541 ty::RePlaceholder(..) => {
1542 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1543 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1544 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1546 ty::ReEarlyBound(..) => {
1547 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1548 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1549 flags = flags | TypeFlags::HAS_RE_PARAM;
1551 ty::ReFree { .. } => {
1552 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1553 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1556 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1558 ty::ReLateBound(..) => {
1559 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1562 flags = flags | TypeFlags::HAS_RE_ERASED;
1566 debug!("type_flags({:?}) = {:?}", self, flags);
1571 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1572 /// For example, consider the regions in this snippet of code:
1574 /// ```ignore (illustrative)
1576 /// // ^^ -- early bound, declared on an impl
1578 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1579 /// // ^^ ^^ ^ anonymous, late-bound
1580 /// // | early-bound, appears in where-clauses
1581 /// // late-bound, appears only in fn args
1586 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1587 /// of the impl, and for all the other highlighted regions, it
1588 /// would return the `DefId` of the function. In other cases (not shown), this
1589 /// function might return the `DefId` of a closure.
1590 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1592 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1593 ty::ReFree(fr) => fr.scope,
1594 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1598 /// True for free regions other than `'static`.
1599 pub fn is_free(self) -> bool {
1600 matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
1603 /// True if `self` is a free region or static.
1604 pub fn is_free_or_static(self) -> bool {
1606 ty::ReStatic => true,
1607 _ => self.is_free(),
1611 pub fn is_var(self) -> bool {
1612 matches!(self.kind(), ty::ReVar(_))
1617 impl<'tcx> Ty<'tcx> {
1619 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1624 pub fn flags(self) -> TypeFlags {
1629 pub fn is_unit(self) -> bool {
1631 Tuple(ref tys) => tys.is_empty(),
1637 pub fn is_never(self) -> bool {
1638 matches!(self.kind(), Never)
1642 pub fn is_primitive(self) -> bool {
1643 self.kind().is_primitive()
1647 pub fn is_adt(self) -> bool {
1648 matches!(self.kind(), Adt(..))
1652 pub fn is_ref(self) -> bool {
1653 matches!(self.kind(), Ref(..))
1657 pub fn is_ty_var(self) -> bool {
1658 matches!(self.kind(), Infer(TyVar(_)))
1662 pub fn ty_vid(self) -> Option<ty::TyVid> {
1664 &Infer(TyVar(vid)) => Some(vid),
1670 pub fn is_ty_infer(self) -> bool {
1671 matches!(self.kind(), Infer(_))
1675 pub fn is_phantom_data(self) -> bool {
1676 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1680 pub fn is_bool(self) -> bool {
1681 *self.kind() == Bool
1684 /// Returns `true` if this type is a `str`.
1686 pub fn is_str(self) -> bool {
1691 pub fn is_param(self, index: u32) -> bool {
1693 ty::Param(ref data) => data.index == index,
1699 pub fn is_slice(self) -> bool {
1700 matches!(self.kind(), Slice(_))
1704 pub fn is_array_slice(self) -> bool {
1707 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1713 pub fn is_array(self) -> bool {
1714 matches!(self.kind(), Array(..))
1718 pub fn is_simd(self) -> bool {
1720 Adt(def, _) => def.repr().simd(),
1725 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1727 Array(ty, _) | Slice(ty) => *ty,
1728 Str => tcx.types.u8,
1729 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1733 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1735 Adt(def, substs) => {
1736 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1737 let variant = def.non_enum_variant();
1738 let f0_ty = variant.fields[0].ty(tcx, substs);
1740 match f0_ty.kind() {
1741 // If the first field is an array, we assume it is the only field and its
1742 // elements are the SIMD components.
1743 Array(f0_elem_ty, f0_len) => {
1744 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1745 // The way we evaluate the `N` in `[T; N]` here only works since we use
1746 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1747 // if we use it in generic code. See the `simd-array-trait` ui test.
1748 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1750 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1751 // all have the same type).
1752 _ => (variant.fields.len() as u64, f0_ty),
1755 _ => bug!("`simd_size_and_type` called on invalid type"),
1760 pub fn is_region_ptr(self) -> bool {
1761 matches!(self.kind(), Ref(..))
1765 pub fn is_mutable_ptr(self) -> bool {
1768 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1769 | Ref(_, _, hir::Mutability::Mut)
1773 /// Get the mutability of the reference or `None` when not a reference
1775 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1777 Ref(_, _, mutability) => Some(*mutability),
1783 pub fn is_unsafe_ptr(self) -> bool {
1784 matches!(self.kind(), RawPtr(_))
1787 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1789 pub fn is_any_ptr(self) -> bool {
1790 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1794 pub fn is_box(self) -> bool {
1796 Adt(def, _) => def.is_box(),
1801 /// Panics if called on any type other than `Box<T>`.
1802 pub fn boxed_ty(self) -> Ty<'tcx> {
1804 Adt(def, substs) if def.is_box() => substs.type_at(0),
1805 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1809 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1810 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1811 /// contents are abstract to rustc.)
1813 pub fn is_scalar(self) -> bool {
1823 | Infer(IntVar(_) | FloatVar(_))
1827 /// Returns `true` if this type is a floating point type.
1829 pub fn is_floating_point(self) -> bool {
1830 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1834 pub fn is_trait(self) -> bool {
1835 matches!(self.kind(), Dynamic(_, _, ty::Dyn))
1839 pub fn is_dyn_star(self) -> bool {
1840 matches!(self.kind(), Dynamic(_, _, ty::DynStar))
1844 pub fn is_enum(self) -> bool {
1845 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1849 pub fn is_union(self) -> bool {
1850 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1854 pub fn is_closure(self) -> bool {
1855 matches!(self.kind(), Closure(..))
1859 pub fn is_generator(self) -> bool {
1860 matches!(self.kind(), Generator(..))
1864 pub fn is_integral(self) -> bool {
1865 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
1869 pub fn is_fresh_ty(self) -> bool {
1870 matches!(self.kind(), Infer(FreshTy(_)))
1874 pub fn is_fresh(self) -> bool {
1875 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
1879 pub fn is_char(self) -> bool {
1880 matches!(self.kind(), Char)
1884 pub fn is_numeric(self) -> bool {
1885 self.is_integral() || self.is_floating_point()
1889 pub fn is_signed(self) -> bool {
1890 matches!(self.kind(), Int(_))
1894 pub fn is_ptr_sized_integral(self) -> bool {
1895 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
1899 pub fn has_concrete_skeleton(self) -> bool {
1900 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
1903 /// Checks whether a type recursively contains another type
1905 /// Example: `Option<()>` contains `()`
1906 pub fn contains(self, other: Ty<'tcx>) -> bool {
1907 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
1909 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
1912 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1913 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
1917 let cf = self.visit_with(&mut ContainsTyVisitor(other));
1921 /// Returns the type and mutability of `*ty`.
1923 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1924 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1925 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1927 Adt(def, _) if def.is_box() => {
1928 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
1930 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
1931 RawPtr(mt) if explicit => Some(*mt),
1936 /// Returns the type of `ty[i]`.
1937 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
1939 Array(ty, _) | Slice(ty) => Some(*ty),
1944 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
1946 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
1949 // ignore errors (#54954)
1950 ty::Binder::dummy(FnSig::fake())
1952 Closure(..) => bug!(
1953 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1955 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
1960 pub fn is_fn(self) -> bool {
1961 matches!(self.kind(), FnDef(..) | FnPtr(_))
1965 pub fn is_fn_ptr(self) -> bool {
1966 matches!(self.kind(), FnPtr(_))
1970 pub fn is_impl_trait(self) -> bool {
1971 matches!(self.kind(), Opaque(..))
1975 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
1977 Adt(adt, _) => Some(*adt),
1982 /// Iterates over tuple fields.
1983 /// Panics when called on anything but a tuple.
1985 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
1987 Tuple(substs) => substs,
1988 _ => bug!("tuple_fields called on non-tuple"),
1992 /// If the type contains variants, returns the valid range of variant indices.
1994 // FIXME: This requires the optimized MIR in the case of generators.
1996 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
1998 TyKind::Adt(adt, _) => Some(adt.variant_range()),
1999 TyKind::Generator(def_id, substs, _) => {
2000 Some(substs.as_generator().variant_range(*def_id, tcx))
2006 /// If the type contains variants, returns the variant for `variant_index`.
2007 /// Panics if `variant_index` is out of range.
2009 // FIXME: This requires the optimized MIR in the case of generators.
2011 pub fn discriminant_for_variant(
2014 variant_index: VariantIdx,
2015 ) -> Option<Discr<'tcx>> {
2017 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2018 // This can actually happen during CTFE, see
2019 // https://github.com/rust-lang/rust/issues/89765.
2022 TyKind::Adt(adt, _) if adt.is_enum() => {
2023 Some(adt.discriminant_for_variant(tcx, variant_index))
2025 TyKind::Generator(def_id, substs, _) => {
2026 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2032 /// Returns the type of the discriminant of this type.
2033 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2035 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2036 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2038 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2039 let assoc_items = tcx.associated_item_def_ids(
2040 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2042 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2061 | ty::GeneratorWitness(..)
2065 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2068 | ty::Placeholder(_)
2069 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2070 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2075 /// Returns the type of metadata for (potentially fat) pointers to this type,
2076 /// and a boolean signifying if this is conditional on this type being `Sized`.
2077 pub fn ptr_metadata_ty(
2080 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2081 ) -> (Ty<'tcx>, bool) {
2082 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2085 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2096 | ty::GeneratorWitness(..)
2101 // Extern types have metadata = ().
2103 // If returned by `struct_tail_without_normalization` this is a unit struct
2104 // without any fields, or not a struct, and therefore is Sized.
2106 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2107 // a.k.a. unit type, which is Sized
2108 | ty::Tuple(..) => (tcx.types.unit, false),
2110 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2111 ty::Dynamic(..) => {
2112 let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, None);
2113 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2116 // type parameters only have unit metadata if they're sized, so return true
2117 // to make sure we double check this during confirmation
2118 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2120 ty::Infer(ty::TyVar(_))
2122 | ty::Placeholder(..)
2123 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2124 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2129 /// When we create a closure, we record its kind (i.e., what trait
2130 /// it implements) into its `ClosureSubsts` using a type
2131 /// parameter. This is kind of a phantom type, except that the
2132 /// most convenient thing for us to are the integral types. This
2133 /// function converts such a special type into the closure
2134 /// kind. To go the other way, use
2135 /// `tcx.closure_kind_ty(closure_kind)`.
2137 /// Note that during type checking, we use an inference variable
2138 /// to represent the closure kind, because it has not yet been
2139 /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
2140 /// is complete, that type variable will be unified.
2141 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2143 Int(int_ty) => match int_ty {
2144 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2145 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2146 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2147 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2150 // "Bound" types appear in canonical queries when the
2151 // closure type is not yet known
2152 Bound(..) | Infer(_) => None,
2154 Error(_) => Some(ty::ClosureKind::Fn),
2156 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2160 /// Fast path helper for testing if a type is `Sized`.
2162 /// Returning true means the type is known to be sized. Returning
2163 /// `false` means nothing -- could be sized, might not be.
2165 /// Note that we could never rely on the fact that a type such as `[_]` is
2166 /// trivially `!Sized` because we could be in a type environment with a
2167 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2168 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2169 /// this method doesn't return `Option<bool>`.
2170 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2172 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2183 | ty::GeneratorWitness(..)
2187 | ty::Error(_) => true,
2189 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2191 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2193 ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(),
2195 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2197 ty::Infer(ty::TyVar(_)) => false,
2200 | ty::Placeholder(..)
2201 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2202 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2207 /// Fast path helper for primitives which are always `Copy` and which
2208 /// have a side-effect-free `Clone` impl.
2210 /// Returning true means the type is known to be pure and `Copy+Clone`.
2211 /// Returning `false` means nothing -- could be `Copy`, might not be.
2213 /// This is mostly useful for optimizations, as there are the types
2214 /// on which we can replace cloning with dereferencing.
2215 pub fn is_trivially_pure_clone_copy(self) -> bool {
2217 ty::Bool | ty::Char | ty::Never => true,
2219 // These aren't even `Clone`
2220 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2222 ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
2225 | ty::Float(..) => true,
2227 // The voldemort ZSTs are fine.
2228 ty::FnDef(..) => true,
2230 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2232 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2233 ty::Tuple(field_tys) => {
2234 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2237 // Sometimes traits aren't implemented for every ABI or arity,
2238 // because we can't be generic over everything yet.
2239 ty::FnPtr(..) => false,
2241 // Definitely absolutely not copy.
2242 ty::Ref(_, _, hir::Mutability::Mut) => false,
2244 // Thin pointers & thin shared references are pure-clone-copy, but for
2245 // anything with custom metadata it might be more complicated.
2246 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2248 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2250 // Might be, but not "trivial" so just giving the safe answer.
2251 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2253 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2255 ty::Bound(..) | ty::Placeholder(..) => {
2256 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2261 // If `self` is a primitive, return its [`Symbol`].
2262 pub fn primitive_symbol(self) -> Option<Symbol> {
2264 ty::Bool => Some(sym::bool),
2265 ty::Char => Some(sym::char),
2266 ty::Float(f) => match f {
2267 ty::FloatTy::F32 => Some(sym::f32),
2268 ty::FloatTy::F64 => Some(sym::f64),
2270 ty::Int(f) => match f {
2271 ty::IntTy::Isize => Some(sym::isize),
2272 ty::IntTy::I8 => Some(sym::i8),
2273 ty::IntTy::I16 => Some(sym::i16),
2274 ty::IntTy::I32 => Some(sym::i32),
2275 ty::IntTy::I64 => Some(sym::i64),
2276 ty::IntTy::I128 => Some(sym::i128),
2278 ty::Uint(f) => match f {
2279 ty::UintTy::Usize => Some(sym::usize),
2280 ty::UintTy::U8 => Some(sym::u8),
2281 ty::UintTy::U16 => Some(sym::u16),
2282 ty::UintTy::U32 => Some(sym::u32),
2283 ty::UintTy::U64 => Some(sym::u64),
2284 ty::UintTy::U128 => Some(sym::u128),
2291 /// Extra information about why we ended up with a particular variance.
2292 /// This is only used to add more information to error messages, and
2293 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2294 /// may lead to confusing notes in error messages, it will never cause
2295 /// a miscompilation or unsoundness.
2297 /// When in doubt, use `VarianceDiagInfo::default()`
2298 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2299 pub enum VarianceDiagInfo<'tcx> {
2300 /// No additional information - this is the default.
2301 /// We will not add any additional information to error messages.
2304 /// We switched our variance because a generic argument occurs inside
2305 /// the invariant generic argument of another type.
2307 /// The generic type containing the generic parameter
2308 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2310 /// The index of the generic parameter being used
2311 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2316 impl<'tcx> VarianceDiagInfo<'tcx> {
2317 /// Mirrors `Variance::xform` - used to 'combine' the existing
2318 /// and new `VarianceDiagInfo`s when our variance changes.
2319 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2320 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2322 VarianceDiagInfo::None => other,
2323 VarianceDiagInfo::Invariant { .. } => self,