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, Subst, 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, Symbol};
23 use rustc_target::abi::VariantIdx;
24 use rustc_target::spec::abi;
26 use std::cmp::Ordering;
28 use std::marker::PhantomData;
29 use std::ops::{ControlFlow, Deref, Range};
30 use ty::util::IntTypeExt;
32 use rustc_type_ir::sty::TyKind::*;
33 use rustc_type_ir::RegionKind as IrRegionKind;
34 use rustc_type_ir::TyKind as IrTyKind;
36 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
37 #[rustc_diagnostic_item = "TyKind"]
38 pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
39 pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
41 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
42 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
43 pub struct TypeAndMut<'tcx> {
45 pub mutbl: hir::Mutability,
48 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
50 /// A "free" region `fr` can be interpreted as "some region
51 /// at least as big as the scope `fr.scope`".
52 pub struct FreeRegion {
54 pub bound_region: BoundRegionKind,
57 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
59 pub enum BoundRegionKind {
60 /// An anonymous region parameter for a given fn (&T)
63 /// Named region parameters for functions (a in &'a T)
65 /// The `DefId` is needed to distinguish free regions in
66 /// the event of shadowing.
67 BrNamed(DefId, Symbol),
69 /// Anonymous region for the implicit env pointer parameter
74 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
76 pub struct BoundRegion {
78 pub kind: BoundRegionKind,
81 impl BoundRegionKind {
82 pub fn is_named(&self) -> bool {
84 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
91 fn article(&self) -> &'static str;
94 impl<'tcx> Article for TyKind<'tcx> {
95 /// Get the article ("a" or "an") to use with this type.
96 fn article(&self) -> &'static str {
98 Int(_) | Float(_) | Array(_, _) => "an",
99 Adt(def, _) if def.is_enum() => "an",
100 // This should never happen, but ICEing and causing the user's code
101 // to not compile felt too harsh.
108 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
109 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
110 static_assert_size!(TyKind<'_>, 32);
112 /// A closure can be modeled as a struct that looks like:
113 /// ```ignore (illustrative)
114 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
118 /// - 'l0...'li and T0...Tj are the generic parameters
119 /// in scope on the function that defined the closure,
120 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
121 /// is rather hackily encoded via a scalar type. See
122 /// `Ty::to_opt_closure_kind` for details.
123 /// - CS represents the *closure signature*, representing as a `fn()`
124 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
125 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
127 /// - U is a type parameter representing the types of its upvars, tupled up
128 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
129 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
131 /// So, for example, given this function:
132 /// ```ignore (illustrative)
133 /// fn foo<'a, T>(data: &'a mut T) {
134 /// do(|| data.count += 1)
137 /// the type of the closure would be something like:
138 /// ```ignore (illustrative)
139 /// struct Closure<'a, T, U>(...U);
141 /// Note that the type of the upvar is not specified in the struct.
142 /// You may wonder how the impl would then be able to use the upvar,
143 /// if it doesn't know it's type? The answer is that the impl is
144 /// (conceptually) not fully generic over Closure but rather tied to
145 /// instances with the expected upvar types:
146 /// ```ignore (illustrative)
147 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
151 /// You can see that the *impl* fully specified the type of the upvar
152 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
153 /// (Here, I am assuming that `data` is mut-borrowed.)
155 /// Now, the last question you may ask is: Why include the upvar types
156 /// in an extra type parameter? The reason for this design is that the
157 /// upvar types can reference lifetimes that are internal to the
158 /// creating function. In my example above, for example, the lifetime
159 /// `'b` represents the scope of the closure itself; this is some
160 /// subset of `foo`, probably just the scope of the call to the to
161 /// `do()`. If we just had the lifetime/type parameters from the
162 /// enclosing function, we couldn't name this lifetime `'b`. Note that
163 /// there can also be lifetimes in the types of the upvars themselves,
164 /// if one of them happens to be a reference to something that the
165 /// creating fn owns.
167 /// OK, you say, so why not create a more minimal set of parameters
168 /// that just includes the extra lifetime parameters? The answer is
169 /// primarily that it would be hard --- we don't know at the time when
170 /// we create the closure type what the full types of the upvars are,
171 /// nor do we know which are borrowed and which are not. In this
172 /// design, we can just supply a fresh type parameter and figure that
175 /// All right, you say, but why include the type parameters from the
176 /// original function then? The answer is that codegen may need them
177 /// when monomorphizing, and they may not appear in the upvars. A
178 /// closure could capture no variables but still make use of some
179 /// in-scope type parameter with a bound (e.g., if our example above
180 /// had an extra `U: Default`, and the closure called `U::default()`).
182 /// There is another reason. This design (implicitly) prohibits
183 /// closures from capturing themselves (except via a trait
184 /// object). This simplifies closure inference considerably, since it
185 /// means that when we infer the kind of a closure or its upvars, we
186 /// don't have to handle cycles where the decisions we make for
187 /// closure C wind up influencing the decisions we ought to make for
188 /// closure C (which would then require fixed point iteration to
189 /// handle). Plus it fixes an ICE. :P
193 /// Generators are handled similarly in `GeneratorSubsts`. The set of
194 /// type parameters is similar, but `CK` and `CS` are replaced by the
195 /// following type parameters:
197 /// * `GS`: The generator's "resume type", which is the type of the
198 /// argument passed to `resume`, and the type of `yield` expressions
199 /// inside the generator.
200 /// * `GY`: The "yield type", which is the type of values passed to
201 /// `yield` inside the generator.
202 /// * `GR`: The "return type", which is the type of value returned upon
203 /// completion of the generator.
204 /// * `GW`: The "generator witness".
205 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
206 pub struct ClosureSubsts<'tcx> {
207 /// Lifetime and type parameters from the enclosing function,
208 /// concatenated with a tuple containing the types of the upvars.
210 /// These are separated out because codegen wants to pass them around
211 /// when monomorphizing.
212 pub substs: SubstsRef<'tcx>,
215 /// Struct returned by `split()`.
216 pub struct ClosureSubstsParts<'tcx, T> {
217 pub parent_substs: &'tcx [GenericArg<'tcx>],
218 pub closure_kind_ty: T,
219 pub closure_sig_as_fn_ptr_ty: T,
220 pub tupled_upvars_ty: T,
223 impl<'tcx> ClosureSubsts<'tcx> {
224 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
225 /// for the closure parent, alongside additional closure-specific components.
228 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
229 ) -> ClosureSubsts<'tcx> {
231 substs: tcx.mk_substs(
232 parts.parent_substs.iter().copied().chain(
233 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
235 .map(|&ty| ty.into()),
241 /// Divides the closure substs into their respective components.
242 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
243 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
244 match self.substs[..] {
246 ref parent_substs @ ..,
248 closure_sig_as_fn_ptr_ty,
250 ] => ClosureSubstsParts {
253 closure_sig_as_fn_ptr_ty,
256 _ => bug!("closure substs missing synthetics"),
260 /// Returns `true` only if enough of the synthetic types are known to
261 /// allow using all of the methods on `ClosureSubsts` without panicking.
263 /// Used primarily by `ty::print::pretty` to be able to handle closure
264 /// types that haven't had their synthetic types substituted in.
265 pub fn is_valid(self) -> bool {
266 self.substs.len() >= 3
267 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
270 /// Returns the substitutions of the closure's parent.
271 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
272 self.split().parent_substs
275 /// Returns an iterator over the list of types of captured paths by the closure.
276 /// In case there was a type error in figuring out the types of the captured path, an
277 /// empty iterator is returned.
279 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
280 match self.tupled_upvars_ty().kind() {
281 TyKind::Error(_) => None,
282 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
283 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
284 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
290 /// Returns the tuple type representing the upvars for this closure.
292 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
293 self.split().tupled_upvars_ty.expect_ty()
296 /// Returns the closure kind for this closure; may return a type
297 /// variable during inference. To get the closure kind during
298 /// inference, use `infcx.closure_kind(substs)`.
299 pub fn kind_ty(self) -> Ty<'tcx> {
300 self.split().closure_kind_ty.expect_ty()
303 /// Returns the `fn` pointer type representing the closure signature for this
305 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
306 // type is known at the time of the creation of `ClosureSubsts`,
307 // see `rustc_typeck::check::closure`.
308 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
309 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
312 /// Returns the closure kind for this closure; only usable outside
313 /// of an inference context, because in that context we know that
314 /// there are no type variables.
316 /// If you have an inference context, use `infcx.closure_kind()`.
317 pub fn kind(self) -> ty::ClosureKind {
318 self.kind_ty().to_opt_closure_kind().unwrap()
321 /// Extracts the signature from the closure.
322 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
323 let ty = self.sig_as_fn_ptr_ty();
325 ty::FnPtr(sig) => *sig,
326 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
330 pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
331 ty::print::PrintClosureAsImpl { closure: self }
335 /// Similar to `ClosureSubsts`; see the above documentation for more.
336 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
337 pub struct GeneratorSubsts<'tcx> {
338 pub substs: SubstsRef<'tcx>,
341 pub struct GeneratorSubstsParts<'tcx, T> {
342 pub parent_substs: &'tcx [GenericArg<'tcx>],
347 pub tupled_upvars_ty: T,
350 impl<'tcx> GeneratorSubsts<'tcx> {
351 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
352 /// for the generator parent, alongside additional generator-specific components.
355 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
356 ) -> GeneratorSubsts<'tcx> {
358 substs: tcx.mk_substs(
359 parts.parent_substs.iter().copied().chain(
365 parts.tupled_upvars_ty,
368 .map(|&ty| ty.into()),
374 /// Divides the generator substs into their respective components.
375 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
376 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
377 match self.substs[..] {
378 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
379 GeneratorSubstsParts {
388 _ => bug!("generator substs missing synthetics"),
392 /// Returns `true` only if enough of the synthetic types are known to
393 /// allow using all of the methods on `GeneratorSubsts` without panicking.
395 /// Used primarily by `ty::print::pretty` to be able to handle generator
396 /// types that haven't had their synthetic types substituted in.
397 pub fn is_valid(self) -> bool {
398 self.substs.len() >= 5
399 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
402 /// Returns the substitutions of the generator's parent.
403 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
404 self.split().parent_substs
407 /// This describes the types that can be contained in a generator.
408 /// It will be a type variable initially and unified in the last stages of typeck of a body.
409 /// It contains a tuple of all the types that could end up on a generator frame.
410 /// The state transformation MIR pass may only produce layouts which mention types
411 /// in this tuple. Upvars are not counted here.
412 pub fn witness(self) -> Ty<'tcx> {
413 self.split().witness.expect_ty()
416 /// Returns an iterator over the list of types of captured paths by the generator.
417 /// In case there was a type error in figuring out the types of the captured path, an
418 /// empty iterator is returned.
420 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
421 match self.tupled_upvars_ty().kind() {
422 TyKind::Error(_) => None,
423 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
424 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
425 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
431 /// Returns the tuple type representing the upvars for this generator.
433 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
434 self.split().tupled_upvars_ty.expect_ty()
437 /// Returns the type representing the resume type of the generator.
438 pub fn resume_ty(self) -> Ty<'tcx> {
439 self.split().resume_ty.expect_ty()
442 /// Returns the type representing the yield type of the generator.
443 pub fn yield_ty(self) -> Ty<'tcx> {
444 self.split().yield_ty.expect_ty()
447 /// Returns the type representing the return type of the generator.
448 pub fn return_ty(self) -> Ty<'tcx> {
449 self.split().return_ty.expect_ty()
452 /// Returns the "generator signature", which consists of its yield
453 /// and return types.
455 /// N.B., some bits of the code prefers to see this wrapped in a
456 /// binder, but it never contains bound regions. Probably this
457 /// function should be removed.
458 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
459 ty::Binder::dummy(self.sig())
462 /// Returns the "generator signature", which consists of its resume, yield
463 /// and return types.
464 pub fn sig(self) -> GenSig<'tcx> {
466 resume_ty: self.resume_ty(),
467 yield_ty: self.yield_ty(),
468 return_ty: self.return_ty(),
473 impl<'tcx> GeneratorSubsts<'tcx> {
474 /// Generator has not been resumed yet.
475 pub const UNRESUMED: usize = 0;
476 /// Generator has returned or is completed.
477 pub const RETURNED: usize = 1;
478 /// Generator has been poisoned.
479 pub const POISONED: usize = 2;
481 const UNRESUMED_NAME: &'static str = "Unresumed";
482 const RETURNED_NAME: &'static str = "Returned";
483 const POISONED_NAME: &'static str = "Panicked";
485 /// The valid variant indices of this generator.
487 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
488 // FIXME requires optimized MIR
489 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
490 VariantIdx::new(0)..VariantIdx::new(num_variants)
493 /// The discriminant for the given variant. Panics if the `variant_index` is
496 pub fn discriminant_for_variant(
500 variant_index: VariantIdx,
502 // Generators don't support explicit discriminant values, so they are
503 // the same as the variant index.
504 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
505 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
508 /// The set of all discriminants for the generator, enumerated with their
511 pub fn discriminants(
515 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
516 self.variant_range(def_id, tcx).map(move |index| {
517 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
521 /// Calls `f` with a reference to the name of the enumerator for the given
523 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
525 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
526 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
527 Self::POISONED => Cow::from(Self::POISONED_NAME),
528 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
532 /// The type of the state discriminant used in the generator type.
534 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
538 /// This returns the types of the MIR locals which had to be stored across suspension points.
539 /// It is calculated in rustc_mir_transform::generator::StateTransform.
540 /// All the types here must be in the tuple in GeneratorInterior.
542 /// The locals are grouped by their variant number. Note that some locals may
543 /// be repeated in multiple variants.
549 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
550 let layout = tcx.generator_layout(def_id).unwrap();
551 layout.variant_fields.iter().map(move |variant| {
554 .map(move |field| EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
558 /// This is the types of the fields of a generator which are not stored in a
561 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
566 #[derive(Debug, Copy, Clone, HashStable)]
567 pub enum UpvarSubsts<'tcx> {
568 Closure(SubstsRef<'tcx>),
569 Generator(SubstsRef<'tcx>),
572 impl<'tcx> UpvarSubsts<'tcx> {
573 /// Returns an iterator over the list of types of captured paths by the closure/generator.
574 /// In case there was a type error in figuring out the types of the captured path, an
575 /// empty iterator is returned.
577 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
578 let tupled_tys = match self {
579 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
580 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
583 match tupled_tys.kind() {
584 TyKind::Error(_) => None,
585 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
586 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
587 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
594 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
596 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
597 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
602 /// An inline const is modeled like
603 /// ```ignore (illustrative)
604 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
608 /// - 'l0...'li and T0...Tj are the generic parameters
609 /// inherited from the item that defined the inline const,
610 /// - R represents the type of the constant.
612 /// When the inline const is instantiated, `R` is substituted as the actual inferred
613 /// type of the constant. The reason that `R` is represented as an extra type parameter
614 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
615 /// inline const can reference lifetimes that are internal to the creating function.
616 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
617 pub struct InlineConstSubsts<'tcx> {
618 /// Generic parameters from the enclosing item,
619 /// concatenated with the inferred type of the constant.
620 pub substs: SubstsRef<'tcx>,
623 /// Struct returned by `split()`.
624 pub struct InlineConstSubstsParts<'tcx, T> {
625 pub parent_substs: &'tcx [GenericArg<'tcx>],
629 impl<'tcx> InlineConstSubsts<'tcx> {
630 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
633 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
634 ) -> InlineConstSubsts<'tcx> {
636 substs: tcx.mk_substs(
637 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
642 /// Divides the inline const substs into their respective components.
643 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
644 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
645 match self.substs[..] {
646 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
647 _ => bug!("inline const substs missing synthetics"),
651 /// Returns the substitutions of the inline const's parent.
652 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
653 self.split().parent_substs
656 /// Returns the type of this inline const.
657 pub fn ty(self) -> Ty<'tcx> {
658 self.split().ty.expect_ty()
662 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
663 #[derive(HashStable, TypeFoldable, TypeVisitable)]
664 pub enum ExistentialPredicate<'tcx> {
665 /// E.g., `Iterator`.
666 Trait(ExistentialTraitRef<'tcx>),
667 /// E.g., `Iterator::Item = T`.
668 Projection(ExistentialProjection<'tcx>),
673 impl<'tcx> ExistentialPredicate<'tcx> {
674 /// Compares via an ordering that will not change if modules are reordered or other changes are
675 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
676 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
677 use self::ExistentialPredicate::*;
678 match (*self, *other) {
679 (Trait(_), Trait(_)) => Ordering::Equal,
680 (Projection(ref a), Projection(ref b)) => {
681 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
683 (AutoTrait(ref a), AutoTrait(ref b)) => {
684 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
686 (Trait(_), _) => Ordering::Less,
687 (Projection(_), Trait(_)) => Ordering::Greater,
688 (Projection(_), _) => Ordering::Less,
689 (AutoTrait(_), _) => Ordering::Greater,
694 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
695 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
696 use crate::ty::ToPredicate;
697 match self.skip_binder() {
698 ExistentialPredicate::Trait(tr) => {
699 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
701 ExistentialPredicate::Projection(p) => {
702 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
704 ExistentialPredicate::AutoTrait(did) => {
705 let trait_ref = self.rebind(ty::TraitRef {
707 substs: tcx.mk_substs_trait(self_ty, &[]),
709 trait_ref.without_const().to_predicate(tcx)
715 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
716 /// Returns the "principal `DefId`" of this set of existential predicates.
718 /// A Rust trait object type consists (in addition to a lifetime bound)
719 /// of a set of trait bounds, which are separated into any number
720 /// of auto-trait bounds, and at most one non-auto-trait bound. The
721 /// non-auto-trait bound is called the "principal" of the trait
724 /// Only the principal can have methods or type parameters (because
725 /// auto traits can have neither of them). This is important, because
726 /// it means the auto traits can be treated as an unordered set (methods
727 /// would force an order for the vtable, while relating traits with
728 /// type parameters without knowing the order to relate them in is
729 /// a rather non-trivial task).
731 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
732 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
733 /// are the set `{Sync}`.
735 /// It is also possible to have a "trivial" trait object that
736 /// consists only of auto traits, with no principal - for example,
737 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
738 /// is `{Send, Sync}`, while there is no principal. These trait objects
739 /// have a "trivial" vtable consisting of just the size, alignment,
741 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
743 .map_bound(|this| match this {
744 ExistentialPredicate::Trait(tr) => Some(tr),
750 pub fn principal_def_id(&self) -> Option<DefId> {
751 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
755 pub fn projection_bounds<'a>(
757 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
758 self.iter().filter_map(|predicate| {
760 .map_bound(|pred| match pred {
761 ExistentialPredicate::Projection(projection) => Some(projection),
769 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'a {
770 self.iter().filter_map(|predicate| match predicate.skip_binder() {
771 ExistentialPredicate::AutoTrait(did) => Some(did),
777 /// A complete reference to a trait. These take numerous guises in syntax,
778 /// but perhaps the most recognizable form is in a where-clause:
779 /// ```ignore (illustrative)
782 /// This would be represented by a trait-reference where the `DefId` is the
783 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
784 /// and `U` as parameter 1.
786 /// Trait references also appear in object types like `Foo<U>`, but in
787 /// that case the `Self` parameter is absent from the substitutions.
788 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
789 #[derive(HashStable, TypeFoldable, TypeVisitable)]
790 pub struct TraitRef<'tcx> {
792 pub substs: SubstsRef<'tcx>,
795 impl<'tcx> TraitRef<'tcx> {
796 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
797 TraitRef { def_id, substs }
800 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
801 /// are the parameters defined on trait.
802 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
803 ty::Binder::dummy(TraitRef {
805 substs: InternalSubsts::identity_for_item(tcx, def_id),
810 pub fn self_ty(&self) -> Ty<'tcx> {
811 self.substs.type_at(0)
817 substs: SubstsRef<'tcx>,
818 ) -> ty::TraitRef<'tcx> {
819 let defs = tcx.generics_of(trait_id);
820 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
824 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
826 impl<'tcx> PolyTraitRef<'tcx> {
827 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
828 self.map_bound_ref(|tr| tr.self_ty())
831 pub fn def_id(&self) -> DefId {
832 self.skip_binder().def_id
835 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
836 self.map_bound(|trait_ref| ty::TraitPredicate {
838 constness: ty::BoundConstness::NotConst,
839 polarity: ty::ImplPolarity::Positive,
843 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
844 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
845 self.map_bound(|trait_ref| ty::TraitPredicate {
847 constness: ty::BoundConstness::NotConst,
848 polarity: ty::ImplPolarity::Negative,
853 impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
854 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
855 self.to_string().into_diagnostic_arg()
859 /// An existential reference to a trait, where `Self` is erased.
860 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
861 /// ```ignore (illustrative)
862 /// exists T. T: Trait<'a, 'b, X, Y>
864 /// The substitutions don't include the erased `Self`, only trait
865 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
866 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
867 #[derive(HashStable, TypeFoldable, TypeVisitable)]
868 pub struct ExistentialTraitRef<'tcx> {
870 pub substs: SubstsRef<'tcx>,
873 impl<'tcx> ExistentialTraitRef<'tcx> {
874 pub fn erase_self_ty(
876 trait_ref: ty::TraitRef<'tcx>,
877 ) -> ty::ExistentialTraitRef<'tcx> {
878 // Assert there is a Self.
879 trait_ref.substs.type_at(0);
881 ty::ExistentialTraitRef {
882 def_id: trait_ref.def_id,
883 substs: tcx.intern_substs(&trait_ref.substs[1..]),
887 /// Object types don't have a self type specified. Therefore, when
888 /// we convert the principal trait-ref into a normal trait-ref,
889 /// you must give *some* self type. A common choice is `mk_err()`
890 /// or some placeholder type.
891 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
892 // otherwise the escaping vars would be captured by the binder
893 // debug_assert!(!self_ty.has_escaping_bound_vars());
895 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
899 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
901 impl<'tcx> PolyExistentialTraitRef<'tcx> {
902 pub fn def_id(&self) -> DefId {
903 self.skip_binder().def_id
906 /// Object types don't have a self type specified. Therefore, when
907 /// we convert the principal trait-ref into a normal trait-ref,
908 /// you must give *some* self type. A common choice is `mk_err()`
909 /// or some placeholder type.
910 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
911 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
915 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
916 #[derive(Encodable, Decodable, HashStable)]
917 pub struct EarlyBinder<T>(pub T);
919 impl<T> EarlyBinder<T> {
920 pub fn as_ref(&self) -> EarlyBinder<&T> {
924 pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<U>
928 self.as_ref().map_bound(f)
931 pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<U>
935 let value = f(self.0);
939 pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<U>, E>
941 F: FnOnce(T) -> Result<U, E>,
943 let value = f(self.0)?;
944 Ok(EarlyBinder(value))
947 pub fn rebind<U>(&self, value: U) -> EarlyBinder<U> {
952 impl<T> EarlyBinder<Option<T>> {
953 pub fn transpose(self) -> Option<EarlyBinder<T>> {
954 self.0.map(|v| EarlyBinder(v))
958 impl<T, U> EarlyBinder<(T, U)> {
959 pub fn transpose_tuple2(self) -> (EarlyBinder<T>, EarlyBinder<U>) {
960 (EarlyBinder(self.0.0), EarlyBinder(self.0.1))
964 pub struct EarlyBinderIter<T> {
968 impl<T: IntoIterator> EarlyBinder<T> {
969 pub fn transpose_iter(self) -> EarlyBinderIter<T::IntoIter> {
970 EarlyBinderIter { t: self.0.into_iter() }
974 impl<T: Iterator> Iterator for EarlyBinderIter<T> {
975 type Item = EarlyBinder<T::Item>;
977 fn next(&mut self) -> Option<Self::Item> {
978 self.t.next().map(|i| EarlyBinder(i))
982 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
983 #[derive(HashStable)]
984 pub enum BoundVariableKind {
986 Region(BoundRegionKind),
990 impl BoundVariableKind {
991 pub fn expect_region(self) -> BoundRegionKind {
993 BoundVariableKind::Region(lt) => lt,
994 _ => bug!("expected a region, but found another kind"),
998 pub fn expect_ty(self) -> BoundTyKind {
1000 BoundVariableKind::Ty(ty) => ty,
1001 _ => bug!("expected a type, but found another kind"),
1005 pub fn expect_const(self) {
1007 BoundVariableKind::Const => (),
1008 _ => bug!("expected a const, but found another kind"),
1013 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
1014 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
1015 /// (which would be represented by the type `PolyTraitRef ==
1016 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
1017 /// erase, or otherwise "discharge" these bound vars, we change the
1018 /// type from `Binder<'tcx, T>` to just `T` (see
1019 /// e.g., `liberate_late_bound_regions`).
1021 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
1022 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1023 #[derive(HashStable)]
1024 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
1026 impl<'tcx, T> Binder<'tcx, T>
1028 T: TypeVisitable<'tcx>,
1030 /// Wraps `value` in a binder, asserting that `value` does not
1031 /// contain any bound vars that would be bound by the
1032 /// binder. This is commonly used to 'inject' a value T into a
1033 /// different binding level.
1034 pub fn dummy(value: T) -> Binder<'tcx, T> {
1035 assert!(!value.has_escaping_bound_vars());
1036 Binder(value, ty::List::empty())
1039 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
1040 if cfg!(debug_assertions) {
1041 let mut validator = ValidateBoundVars::new(vars);
1042 value.visit_with(&mut validator);
1048 impl<'tcx, T> Binder<'tcx, T> {
1049 /// Skips the binder and returns the "bound" value. This is a
1050 /// risky thing to do because it's easy to get confused about
1051 /// De Bruijn indices and the like. It is usually better to
1052 /// discharge the binder using `no_bound_vars` or
1053 /// `replace_late_bound_regions` or something like
1054 /// that. `skip_binder` is only valid when you are either
1055 /// extracting data that has nothing to do with bound vars, you
1056 /// are doing some sort of test that does not involve bound
1057 /// regions, or you are being very careful about your depth
1060 /// Some examples where `skip_binder` is reasonable:
1062 /// - extracting the `DefId` from a PolyTraitRef;
1063 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1064 /// a type parameter `X`, since the type `X` does not reference any regions
1065 pub fn skip_binder(self) -> T {
1069 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1073 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1074 Binder(&self.0, self.1)
1077 pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
1081 Binder(&self.0, self.1)
1084 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1088 let value = f(&self.0);
1089 Binder(value, self.1)
1092 pub fn map_bound_ref<F, U: TypeVisitable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1096 self.as_ref().map_bound(f)
1099 pub fn map_bound<F, U: TypeVisitable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1103 let value = f(self.0);
1104 if cfg!(debug_assertions) {
1105 let mut validator = ValidateBoundVars::new(self.1);
1106 value.visit_with(&mut validator);
1108 Binder(value, self.1)
1111 pub fn try_map_bound<F, U: TypeVisitable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1113 F: FnOnce(T) -> Result<U, E>,
1115 let value = f(self.0)?;
1116 if cfg!(debug_assertions) {
1117 let mut validator = ValidateBoundVars::new(self.1);
1118 value.visit_with(&mut validator);
1120 Ok(Binder(value, self.1))
1123 /// Wraps a `value` in a binder, using the same bound variables as the
1124 /// current `Binder`. This should not be used if the new value *changes*
1125 /// the bound variables. Note: the (old or new) value itself does not
1126 /// necessarily need to *name* all the bound variables.
1128 /// This currently doesn't do anything different than `bind`, because we
1129 /// don't actually track bound vars. However, semantically, it is different
1130 /// because bound vars aren't allowed to change here, whereas they are
1131 /// in `bind`. This may be (debug) asserted in the future.
1132 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1134 U: TypeVisitable<'tcx>,
1136 if cfg!(debug_assertions) {
1137 let mut validator = ValidateBoundVars::new(self.bound_vars());
1138 value.visit_with(&mut validator);
1140 Binder(value, self.1)
1143 /// Unwraps and returns the value within, but only if it contains
1144 /// no bound vars at all. (In other words, if this binder --
1145 /// and indeed any enclosing binder -- doesn't bind anything at
1146 /// all.) Otherwise, returns `None`.
1148 /// (One could imagine having a method that just unwraps a single
1149 /// binder, but permits late-bound vars bound by enclosing
1150 /// binders, but that would require adjusting the debruijn
1151 /// indices, and given the shallow binding structure we often use,
1152 /// would not be that useful.)
1153 pub fn no_bound_vars(self) -> Option<T>
1155 T: TypeVisitable<'tcx>,
1157 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1160 /// Splits the contents into two things that share the same binder
1161 /// level as the original, returning two distinct binders.
1163 /// `f` should consider bound regions at depth 1 to be free, and
1164 /// anything it produces with bound regions at depth 1 will be
1165 /// bound in the resulting return values.
1166 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1168 F: FnOnce(T) -> (U, V),
1170 let (u, v) = f(self.0);
1171 (Binder(u, self.1), Binder(v, self.1))
1175 impl<'tcx, T> Binder<'tcx, Option<T>> {
1176 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1177 let bound_vars = self.1;
1178 self.0.map(|v| Binder(v, bound_vars))
1182 /// Represents the projection of an associated type. In explicit UFCS
1183 /// form this would be written `<T as Trait<..>>::N`.
1184 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1185 #[derive(HashStable, TypeFoldable, TypeVisitable)]
1186 pub struct ProjectionTy<'tcx> {
1187 /// The parameters of the associated item.
1188 pub substs: SubstsRef<'tcx>,
1190 /// The `DefId` of the `TraitItem` for the associated type `N`.
1192 /// Note that this is not the `DefId` of the `TraitRef` containing this
1193 /// associated type, which is in `tcx.associated_item(item_def_id).container`,
1194 /// aka. `tcx.parent(item_def_id).unwrap()`.
1195 pub item_def_id: DefId,
1198 impl<'tcx> ProjectionTy<'tcx> {
1199 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1200 let parent = tcx.parent(self.item_def_id);
1201 assert_eq!(tcx.def_kind(parent), DefKind::Trait);
1205 /// Extracts the underlying trait reference and own substs from this projection.
1206 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1207 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1208 pub fn trait_ref_and_own_substs(
1211 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1212 let def_id = tcx.parent(self.item_def_id);
1213 let trait_generics = tcx.generics_of(def_id);
1215 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1216 &self.substs[trait_generics.count()..],
1220 /// Extracts the underlying trait reference from this projection.
1221 /// For example, if this is a projection of `<T as Iterator>::Item`,
1222 /// then this function would return a `T: Iterator` trait reference.
1224 /// WARNING: This will drop the substs for generic associated types
1225 /// consider calling [Self::trait_ref_and_own_substs] to get those
1227 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1228 let def_id = self.trait_def_id(tcx);
1229 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1232 pub fn self_ty(&self) -> Ty<'tcx> {
1233 self.substs.type_at(0)
1237 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
1238 pub struct GenSig<'tcx> {
1239 pub resume_ty: Ty<'tcx>,
1240 pub yield_ty: Ty<'tcx>,
1241 pub return_ty: Ty<'tcx>,
1244 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1246 /// Signature of a function type, which we have arbitrarily
1247 /// decided to use to refer to the input/output types.
1249 /// - `inputs`: is the list of arguments and their modes.
1250 /// - `output`: is the return type.
1251 /// - `c_variadic`: indicates whether this is a C-variadic function.
1252 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1253 #[derive(HashStable, TypeFoldable, TypeVisitable)]
1254 pub struct FnSig<'tcx> {
1255 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1256 pub c_variadic: bool,
1257 pub unsafety: hir::Unsafety,
1261 impl<'tcx> FnSig<'tcx> {
1262 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1263 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1266 pub fn output(&self) -> Ty<'tcx> {
1267 self.inputs_and_output[self.inputs_and_output.len() - 1]
1270 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1272 fn fake() -> FnSig<'tcx> {
1274 inputs_and_output: List::empty(),
1276 unsafety: hir::Unsafety::Normal,
1277 abi: abi::Abi::Rust,
1282 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1284 impl<'tcx> PolyFnSig<'tcx> {
1286 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1287 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1290 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1291 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1293 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1294 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1297 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1298 self.map_bound_ref(|fn_sig| fn_sig.output())
1300 pub fn c_variadic(&self) -> bool {
1301 self.skip_binder().c_variadic
1303 pub fn unsafety(&self) -> hir::Unsafety {
1304 self.skip_binder().unsafety
1306 pub fn abi(&self) -> abi::Abi {
1307 self.skip_binder().abi
1311 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1313 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1314 #[derive(HashStable)]
1315 pub struct ParamTy {
1320 impl<'tcx> ParamTy {
1321 pub fn new(index: u32, name: Symbol) -> ParamTy {
1322 ParamTy { index, name }
1325 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1326 ParamTy::new(def.index, def.name)
1330 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1331 tcx.mk_ty_param(self.index, self.name)
1335 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1336 #[derive(HashStable)]
1337 pub struct ParamConst {
1343 pub fn new(index: u32, name: Symbol) -> ParamConst {
1344 ParamConst { index, name }
1347 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1348 ParamConst::new(def.index, def.name)
1352 /// Use this rather than `RegionKind`, whenever possible.
1353 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1354 #[rustc_pass_by_value]
1355 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
1357 impl<'tcx> Deref for Region<'tcx> {
1358 type Target = RegionKind<'tcx>;
1361 fn deref(&self) -> &RegionKind<'tcx> {
1366 impl<'tcx> fmt::Debug for Region<'tcx> {
1367 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1368 write!(f, "{:?}", self.kind())
1372 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1373 #[derive(HashStable)]
1374 pub struct EarlyBoundRegion {
1380 impl fmt::Debug for EarlyBoundRegion {
1381 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1382 write!(f, "{}, {}", self.index, self.name)
1386 /// A **`const`** **v**ariable **ID**.
1387 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1388 #[derive(HashStable, TyEncodable, TyDecodable)]
1389 pub struct ConstVid<'tcx> {
1391 pub phantom: PhantomData<&'tcx ()>,
1394 rustc_index::newtype_index! {
1395 /// A **region** (lifetime) **v**ariable **ID**.
1396 #[derive(HashStable)]
1397 pub struct RegionVid {
1398 DEBUG_FORMAT = custom,
1402 impl Atom for RegionVid {
1403 fn index(self) -> usize {
1408 rustc_index::newtype_index! {
1409 #[derive(HashStable)]
1410 pub struct BoundVar { .. }
1413 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1414 #[derive(HashStable)]
1415 pub struct BoundTy {
1417 pub kind: BoundTyKind,
1420 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1421 #[derive(HashStable)]
1422 pub enum BoundTyKind {
1427 impl From<BoundVar> for BoundTy {
1428 fn from(var: BoundVar) -> Self {
1429 BoundTy { var, kind: BoundTyKind::Anon }
1433 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1434 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1435 #[derive(HashStable, TypeFoldable, TypeVisitable)]
1436 pub struct ExistentialProjection<'tcx> {
1437 pub item_def_id: DefId,
1438 pub substs: SubstsRef<'tcx>,
1439 pub term: Term<'tcx>,
1442 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1444 impl<'tcx> ExistentialProjection<'tcx> {
1445 /// Extracts the underlying existential trait reference from this projection.
1446 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1447 /// then this function would return an `exists T. T: Iterator` existential trait
1449 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1450 let def_id = tcx.parent(self.item_def_id);
1451 let subst_count = tcx.generics_of(def_id).count() - 1;
1452 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1453 ty::ExistentialTraitRef { def_id, substs }
1456 pub fn with_self_ty(
1460 ) -> ty::ProjectionPredicate<'tcx> {
1461 // otherwise the escaping regions would be captured by the binders
1462 debug_assert!(!self_ty.has_escaping_bound_vars());
1464 ty::ProjectionPredicate {
1465 projection_ty: ty::ProjectionTy {
1466 item_def_id: self.item_def_id,
1467 substs: tcx.mk_substs_trait(self_ty, self.substs),
1473 pub fn erase_self_ty(
1475 projection_predicate: ty::ProjectionPredicate<'tcx>,
1477 // Assert there is a Self.
1478 projection_predicate.projection_ty.substs.type_at(0);
1481 item_def_id: projection_predicate.projection_ty.item_def_id,
1482 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1483 term: projection_predicate.term,
1488 impl<'tcx> PolyExistentialProjection<'tcx> {
1489 pub fn with_self_ty(
1493 ) -> ty::PolyProjectionPredicate<'tcx> {
1494 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1497 pub fn item_def_id(&self) -> DefId {
1498 self.skip_binder().item_def_id
1502 /// Region utilities
1503 impl<'tcx> Region<'tcx> {
1504 pub fn kind(self) -> RegionKind<'tcx> {
1508 /// Is this region named by the user?
1509 pub fn has_name(self) -> bool {
1511 ty::ReEarlyBound(ebr) => ebr.has_name(),
1512 ty::ReLateBound(_, br) => br.kind.is_named(),
1513 ty::ReFree(fr) => fr.bound_region.is_named(),
1514 ty::ReStatic => true,
1515 ty::ReVar(..) => false,
1516 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1517 ty::ReEmpty(_) => false,
1518 ty::ReErased => false,
1523 pub fn is_static(self) -> bool {
1524 matches!(*self, ty::ReStatic)
1528 pub fn is_erased(self) -> bool {
1529 matches!(*self, ty::ReErased)
1533 pub fn is_late_bound(self) -> bool {
1534 matches!(*self, ty::ReLateBound(..))
1538 pub fn is_placeholder(self) -> bool {
1539 matches!(*self, ty::RePlaceholder(..))
1543 pub fn is_empty(self) -> bool {
1544 matches!(*self, ty::ReEmpty(..))
1548 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1550 ty::ReLateBound(debruijn, _) => debruijn >= index,
1555 pub fn type_flags(self) -> TypeFlags {
1556 let mut flags = TypeFlags::empty();
1560 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1561 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1562 flags = flags | TypeFlags::HAS_RE_INFER;
1564 ty::RePlaceholder(..) => {
1565 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1566 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1567 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1569 ty::ReEarlyBound(..) => {
1570 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1571 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1572 flags = flags | TypeFlags::HAS_RE_PARAM;
1574 ty::ReFree { .. } => {
1575 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1576 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1578 ty::ReEmpty(_) | ty::ReStatic => {
1579 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1581 ty::ReLateBound(..) => {
1582 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1585 flags = flags | TypeFlags::HAS_RE_ERASED;
1589 debug!("type_flags({:?}) = {:?}", self, flags);
1594 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1595 /// For example, consider the regions in this snippet of code:
1597 /// ```ignore (illustrative)
1599 /// // ^^ -- early bound, declared on an impl
1601 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1602 /// // ^^ ^^ ^ anonymous, late-bound
1603 /// // | early-bound, appears in where-clauses
1604 /// // late-bound, appears only in fn args
1609 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1610 /// of the impl, and for all the other highlighted regions, it
1611 /// would return the `DefId` of the function. In other cases (not shown), this
1612 /// function might return the `DefId` of a closure.
1613 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1615 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1616 ty::ReFree(fr) => fr.scope,
1617 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1621 /// True for free regions other than `'static`.
1622 pub fn is_free(self) -> bool {
1623 matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
1626 /// True if `self` is a free region or static.
1627 pub fn is_free_or_static(self) -> bool {
1629 ty::ReStatic => true,
1630 _ => self.is_free(),
1634 pub fn is_var(self) -> bool {
1635 matches!(self.kind(), ty::ReVar(_))
1640 impl<'tcx> Ty<'tcx> {
1642 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1647 pub fn flags(self) -> TypeFlags {
1652 pub fn is_unit(self) -> bool {
1654 Tuple(ref tys) => tys.is_empty(),
1660 pub fn is_never(self) -> bool {
1661 matches!(self.kind(), Never)
1665 pub fn is_primitive(self) -> bool {
1666 self.kind().is_primitive()
1670 pub fn is_adt(self) -> bool {
1671 matches!(self.kind(), Adt(..))
1675 pub fn is_ref(self) -> bool {
1676 matches!(self.kind(), Ref(..))
1680 pub fn is_ty_var(self) -> bool {
1681 matches!(self.kind(), Infer(TyVar(_)))
1685 pub fn ty_vid(self) -> Option<ty::TyVid> {
1687 &Infer(TyVar(vid)) => Some(vid),
1693 pub fn is_ty_infer(self) -> bool {
1694 matches!(self.kind(), Infer(_))
1698 pub fn is_phantom_data(self) -> bool {
1699 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1703 pub fn is_bool(self) -> bool {
1704 *self.kind() == Bool
1707 /// Returns `true` if this type is a `str`.
1709 pub fn is_str(self) -> bool {
1714 pub fn is_param(self, index: u32) -> bool {
1716 ty::Param(ref data) => data.index == index,
1722 pub fn is_slice(self) -> bool {
1723 matches!(self.kind(), Slice(_))
1727 pub fn is_array_slice(self) -> bool {
1730 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1736 pub fn is_array(self) -> bool {
1737 matches!(self.kind(), Array(..))
1741 pub fn is_simd(self) -> bool {
1743 Adt(def, _) => def.repr().simd(),
1748 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1750 Array(ty, _) | Slice(ty) => *ty,
1751 Str => tcx.types.u8,
1752 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1756 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1758 Adt(def, substs) => {
1759 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1760 let variant = def.non_enum_variant();
1761 let f0_ty = variant.fields[0].ty(tcx, substs);
1763 match f0_ty.kind() {
1764 // If the first field is an array, we assume it is the only field and its
1765 // elements are the SIMD components.
1766 Array(f0_elem_ty, f0_len) => {
1767 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1768 // The way we evaluate the `N` in `[T; N]` here only works since we use
1769 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1770 // if we use it in generic code. See the `simd-array-trait` ui test.
1771 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1773 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1774 // all have the same type).
1775 _ => (variant.fields.len() as u64, f0_ty),
1778 _ => bug!("`simd_size_and_type` called on invalid type"),
1783 pub fn is_region_ptr(self) -> bool {
1784 matches!(self.kind(), Ref(..))
1788 pub fn is_mutable_ptr(self) -> bool {
1791 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1792 | Ref(_, _, hir::Mutability::Mut)
1796 /// Get the mutability of the reference or `None` when not a reference
1798 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1800 Ref(_, _, mutability) => Some(*mutability),
1806 pub fn is_unsafe_ptr(self) -> bool {
1807 matches!(self.kind(), RawPtr(_))
1810 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1812 pub fn is_any_ptr(self) -> bool {
1813 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1817 pub fn is_box(self) -> bool {
1819 Adt(def, _) => def.is_box(),
1824 /// Panics if called on any type other than `Box<T>`.
1825 pub fn boxed_ty(self) -> Ty<'tcx> {
1827 Adt(def, substs) if def.is_box() => substs.type_at(0),
1828 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1832 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1833 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1834 /// contents are abstract to rustc.)
1836 pub fn is_scalar(self) -> bool {
1846 | Infer(IntVar(_) | FloatVar(_))
1850 /// Returns `true` if this type is a floating point type.
1852 pub fn is_floating_point(self) -> bool {
1853 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1857 pub fn is_trait(self) -> bool {
1858 matches!(self.kind(), Dynamic(..))
1862 pub fn is_enum(self) -> bool {
1863 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1867 pub fn is_union(self) -> bool {
1868 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1872 pub fn is_closure(self) -> bool {
1873 matches!(self.kind(), Closure(..))
1877 pub fn is_generator(self) -> bool {
1878 matches!(self.kind(), Generator(..))
1882 pub fn is_integral(self) -> bool {
1883 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
1887 pub fn is_fresh_ty(self) -> bool {
1888 matches!(self.kind(), Infer(FreshTy(_)))
1892 pub fn is_fresh(self) -> bool {
1893 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
1897 pub fn is_char(self) -> bool {
1898 matches!(self.kind(), Char)
1902 pub fn is_numeric(self) -> bool {
1903 self.is_integral() || self.is_floating_point()
1907 pub fn is_signed(self) -> bool {
1908 matches!(self.kind(), Int(_))
1912 pub fn is_ptr_sized_integral(self) -> bool {
1913 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
1917 pub fn has_concrete_skeleton(self) -> bool {
1918 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
1921 /// Checks whether a type recursively contains another type
1923 /// Example: `Option<()>` contains `()`
1924 pub fn contains(self, other: Ty<'tcx>) -> bool {
1925 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
1927 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
1930 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1931 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
1935 let cf = self.visit_with(&mut ContainsTyVisitor(other));
1939 /// Returns the type and mutability of `*ty`.
1941 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1942 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1943 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1945 Adt(def, _) if def.is_box() => {
1946 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
1948 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
1949 RawPtr(mt) if explicit => Some(*mt),
1954 /// Returns the type of `ty[i]`.
1955 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
1957 Array(ty, _) | Slice(ty) => Some(*ty),
1962 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
1964 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
1967 // ignore errors (#54954)
1968 ty::Binder::dummy(FnSig::fake())
1970 Closure(..) => bug!(
1971 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1973 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
1978 pub fn is_fn(self) -> bool {
1979 matches!(self.kind(), FnDef(..) | FnPtr(_))
1983 pub fn is_fn_ptr(self) -> bool {
1984 matches!(self.kind(), FnPtr(_))
1988 pub fn is_impl_trait(self) -> bool {
1989 matches!(self.kind(), Opaque(..))
1993 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
1995 Adt(adt, _) => Some(*adt),
2000 /// Iterates over tuple fields.
2001 /// Panics when called on anything but a tuple.
2003 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
2005 Tuple(substs) => substs,
2006 _ => bug!("tuple_fields called on non-tuple"),
2010 /// If the type contains variants, returns the valid range of variant indices.
2012 // FIXME: This requires the optimized MIR in the case of generators.
2014 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2016 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2017 TyKind::Generator(def_id, substs, _) => {
2018 Some(substs.as_generator().variant_range(*def_id, tcx))
2024 /// If the type contains variants, returns the variant for `variant_index`.
2025 /// Panics if `variant_index` is out of range.
2027 // FIXME: This requires the optimized MIR in the case of generators.
2029 pub fn discriminant_for_variant(
2032 variant_index: VariantIdx,
2033 ) -> Option<Discr<'tcx>> {
2035 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2036 // This can actually happen during CTFE, see
2037 // https://github.com/rust-lang/rust/issues/89765.
2040 TyKind::Adt(adt, _) if adt.is_enum() => {
2041 Some(adt.discriminant_for_variant(tcx, variant_index))
2043 TyKind::Generator(def_id, substs, _) => {
2044 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2050 /// Returns the type of the discriminant of this type.
2051 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2053 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2054 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2056 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2057 let assoc_items = tcx.associated_item_def_ids(
2058 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2060 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2079 | ty::GeneratorWitness(..)
2083 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2086 | ty::Placeholder(_)
2087 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2088 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2093 /// Returns the type of metadata for (potentially fat) pointers to this type,
2094 /// and a boolean signifying if this is conditional on this type being `Sized`.
2095 pub fn ptr_metadata_ty(
2098 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2099 ) -> (Ty<'tcx>, bool) {
2100 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2103 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2114 | ty::GeneratorWitness(..)
2119 // Extern types have metadata = ().
2121 // If returned by `struct_tail_without_normalization` this is a unit struct
2122 // without any fields, or not a struct, and therefore is Sized.
2124 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2125 // a.k.a. unit type, which is Sized
2126 | ty::Tuple(..) => (tcx.types.unit, false),
2128 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2129 ty::Dynamic(..) => {
2130 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2131 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2134 // type parameters only have unit metadata if they're sized, so return true
2135 // to make sure we double check this during confirmation
2136 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2138 ty::Infer(ty::TyVar(_))
2140 | ty::Placeholder(..)
2141 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2142 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2147 /// When we create a closure, we record its kind (i.e., what trait
2148 /// it implements) into its `ClosureSubsts` using a type
2149 /// parameter. This is kind of a phantom type, except that the
2150 /// most convenient thing for us to are the integral types. This
2151 /// function converts such a special type into the closure
2152 /// kind. To go the other way, use
2153 /// `tcx.closure_kind_ty(closure_kind)`.
2155 /// Note that during type checking, we use an inference variable
2156 /// to represent the closure kind, because it has not yet been
2157 /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
2158 /// is complete, that type variable will be unified.
2159 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2161 Int(int_ty) => match int_ty {
2162 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2163 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2164 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2165 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2168 // "Bound" types appear in canonical queries when the
2169 // closure type is not yet known
2170 Bound(..) | Infer(_) => None,
2172 Error(_) => Some(ty::ClosureKind::Fn),
2174 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2178 /// Fast path helper for testing if a type is `Sized`.
2180 /// Returning true means the type is known to be sized. Returning
2181 /// `false` means nothing -- could be sized, might not be.
2183 /// Note that we could never rely on the fact that a type such as `[_]` is
2184 /// trivially `!Sized` because we could be in a type environment with a
2185 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2186 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2187 /// this method doesn't return `Option<bool>`.
2188 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2190 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2201 | ty::GeneratorWitness(..)
2205 | ty::Error(_) => true,
2207 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2209 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2211 ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(),
2213 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2215 ty::Infer(ty::TyVar(_)) => false,
2218 | ty::Placeholder(..)
2219 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2220 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2225 /// Fast path helper for primitives which are always `Copy` and which
2226 /// have a side-effect-free `Clone` impl.
2228 /// Returning true means the type is known to be pure and `Copy+Clone`.
2229 /// Returning `false` means nothing -- could be `Copy`, might not be.
2231 /// This is mostly useful for optimizations, as there are the types
2232 /// on which we can replace cloning with dereferencing.
2233 pub fn is_trivially_pure_clone_copy(self) -> bool {
2235 ty::Bool | ty::Char | ty::Never => true,
2237 // These aren't even `Clone`
2238 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2240 ty::Int(..) | ty::Uint(..) | ty::Float(..) => true,
2242 // The voldemort ZSTs are fine.
2243 ty::FnDef(..) => true,
2245 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2247 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2248 ty::Tuple(field_tys) => {
2249 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2252 // Sometimes traits aren't implemented for every ABI or arity,
2253 // because we can't be generic over everything yet.
2254 ty::FnPtr(..) => false,
2256 // Definitely absolutely not copy.
2257 ty::Ref(_, _, hir::Mutability::Mut) => false,
2259 // Thin pointers & thin shared references are pure-clone-copy, but for
2260 // anything with custom metadata it might be more complicated.
2261 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2263 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2265 // Might be, but not "trivial" so just giving the safe answer.
2266 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2268 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2270 ty::Bound(..) | ty::Placeholder(..) => {
2271 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2277 /// Extra information about why we ended up with a particular variance.
2278 /// This is only used to add more information to error messages, and
2279 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2280 /// may lead to confusing notes in error messages, it will never cause
2281 /// a miscompilation or unsoundness.
2283 /// When in doubt, use `VarianceDiagInfo::default()`
2284 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2285 pub enum VarianceDiagInfo<'tcx> {
2286 /// No additional information - this is the default.
2287 /// We will not add any additional information to error messages.
2290 /// We switched our variance because a generic argument occurs inside
2291 /// the invariant generic argument of another type.
2293 /// The generic type containing the generic parameter
2294 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2296 /// The index of the generic parameter being used
2297 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2302 impl<'tcx> VarianceDiagInfo<'tcx> {
2303 /// Mirrors `Variance::xform` - used to 'combine' the existing
2304 /// and new `VarianceDiagInfo`s when our variance changes.
2305 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2306 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2308 VarianceDiagInfo::None => other,
2309 VarianceDiagInfo::Invariant { .. } => self,