1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
5 use crate::infer::canonical::Canonical;
6 use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
7 use crate::ty::visit::ValidateBoundVars;
8 use crate::ty::InferTy::*;
10 self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeSuperVisitable, TypeVisitable,
13 use crate::ty::{List, ParamEnv};
14 use hir::def::DefKind;
15 use polonius_engine::Atom;
16 use rustc_data_structures::captures::Captures;
17 use rustc_data_structures::intern::Interned;
19 use rustc_hir::def_id::DefId;
20 use rustc_index::vec::Idx;
21 use rustc_macros::HashStable;
22 use rustc_span::symbol::{kw, sym, Symbol};
24 use rustc_target::abi::VariantIdx;
25 use rustc_target::spec::abi;
27 use std::cmp::Ordering;
29 use std::marker::PhantomData;
30 use std::ops::{ControlFlow, Deref, Range};
31 use ty::util::IntTypeExt;
33 use rustc_type_ir::sty::TyKind::*;
34 use rustc_type_ir::RegionKind as IrRegionKind;
35 use rustc_type_ir::TyKind as IrTyKind;
37 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
38 #[rustc_diagnostic_item = "TyKind"]
39 pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
40 pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
42 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
43 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
44 pub struct TypeAndMut<'tcx> {
46 pub mutbl: hir::Mutability,
49 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
51 /// A "free" region `fr` can be interpreted as "some region
52 /// at least as big as the scope `fr.scope`".
53 pub struct FreeRegion {
55 pub bound_region: BoundRegionKind,
58 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
60 pub enum BoundRegionKind {
61 /// An anonymous region parameter for a given fn (&T)
62 BrAnon(u32, Option<Span>),
64 /// Named region parameters for functions (a in &'a T)
66 /// The `DefId` is needed to distinguish free regions in
67 /// the event of shadowing.
68 BrNamed(DefId, Symbol),
70 /// Anonymous region for the implicit env pointer parameter
75 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
77 pub struct BoundRegion {
79 pub kind: BoundRegionKind,
82 impl BoundRegionKind {
83 pub fn is_named(&self) -> bool {
85 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
90 pub fn get_name(&self) -> Option<Symbol> {
93 BoundRegionKind::BrNamed(_, name) => return Some(name),
103 fn article(&self) -> &'static str;
106 impl<'tcx> Article for TyKind<'tcx> {
107 /// Get the article ("a" or "an") to use with this type.
108 fn article(&self) -> &'static str {
110 Int(_) | Float(_) | Array(_, _) => "an",
111 Adt(def, _) if def.is_enum() => "an",
112 // This should never happen, but ICEing and causing the user's code
113 // to not compile felt too harsh.
120 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
121 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
122 static_assert_size!(TyKind<'_>, 32);
124 /// A closure can be modeled as a struct that looks like:
125 /// ```ignore (illustrative)
126 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
130 /// - 'l0...'li and T0...Tj are the generic parameters
131 /// in scope on the function that defined the closure,
132 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
133 /// is rather hackily encoded via a scalar type. See
134 /// `Ty::to_opt_closure_kind` for details.
135 /// - CS represents the *closure signature*, representing as a `fn()`
136 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
137 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
139 /// - U is a type parameter representing the types of its upvars, tupled up
140 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
141 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
143 /// So, for example, given this function:
144 /// ```ignore (illustrative)
145 /// fn foo<'a, T>(data: &'a mut T) {
146 /// do(|| data.count += 1)
149 /// the type of the closure would be something like:
150 /// ```ignore (illustrative)
151 /// struct Closure<'a, T, U>(...U);
153 /// Note that the type of the upvar is not specified in the struct.
154 /// You may wonder how the impl would then be able to use the upvar,
155 /// if it doesn't know it's type? The answer is that the impl is
156 /// (conceptually) not fully generic over Closure but rather tied to
157 /// instances with the expected upvar types:
158 /// ```ignore (illustrative)
159 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
163 /// You can see that the *impl* fully specified the type of the upvar
164 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
165 /// (Here, I am assuming that `data` is mut-borrowed.)
167 /// Now, the last question you may ask is: Why include the upvar types
168 /// in an extra type parameter? The reason for this design is that the
169 /// upvar types can reference lifetimes that are internal to the
170 /// creating function. In my example above, for example, the lifetime
171 /// `'b` represents the scope of the closure itself; this is some
172 /// subset of `foo`, probably just the scope of the call to the to
173 /// `do()`. If we just had the lifetime/type parameters from the
174 /// enclosing function, we couldn't name this lifetime `'b`. Note that
175 /// there can also be lifetimes in the types of the upvars themselves,
176 /// if one of them happens to be a reference to something that the
177 /// creating fn owns.
179 /// OK, you say, so why not create a more minimal set of parameters
180 /// that just includes the extra lifetime parameters? The answer is
181 /// primarily that it would be hard --- we don't know at the time when
182 /// we create the closure type what the full types of the upvars are,
183 /// nor do we know which are borrowed and which are not. In this
184 /// design, we can just supply a fresh type parameter and figure that
187 /// All right, you say, but why include the type parameters from the
188 /// original function then? The answer is that codegen may need them
189 /// when monomorphizing, and they may not appear in the upvars. A
190 /// closure could capture no variables but still make use of some
191 /// in-scope type parameter with a bound (e.g., if our example above
192 /// had an extra `U: Default`, and the closure called `U::default()`).
194 /// There is another reason. This design (implicitly) prohibits
195 /// closures from capturing themselves (except via a trait
196 /// object). This simplifies closure inference considerably, since it
197 /// means that when we infer the kind of a closure or its upvars, we
198 /// don't have to handle cycles where the decisions we make for
199 /// closure C wind up influencing the decisions we ought to make for
200 /// closure C (which would then require fixed point iteration to
201 /// handle). Plus it fixes an ICE. :P
205 /// Generators are handled similarly in `GeneratorSubsts`. The set of
206 /// type parameters is similar, but `CK` and `CS` are replaced by the
207 /// following type parameters:
209 /// * `GS`: The generator's "resume type", which is the type of the
210 /// argument passed to `resume`, and the type of `yield` expressions
211 /// inside the generator.
212 /// * `GY`: The "yield type", which is the type of values passed to
213 /// `yield` inside the generator.
214 /// * `GR`: The "return type", which is the type of value returned upon
215 /// completion of the generator.
216 /// * `GW`: The "generator witness".
217 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
218 pub struct ClosureSubsts<'tcx> {
219 /// Lifetime and type parameters from the enclosing function,
220 /// concatenated with a tuple containing the types of the upvars.
222 /// These are separated out because codegen wants to pass them around
223 /// when monomorphizing.
224 pub substs: SubstsRef<'tcx>,
227 /// Struct returned by `split()`.
228 pub struct ClosureSubstsParts<'tcx, T> {
229 pub parent_substs: &'tcx [GenericArg<'tcx>],
230 pub closure_kind_ty: T,
231 pub closure_sig_as_fn_ptr_ty: T,
232 pub tupled_upvars_ty: T,
235 impl<'tcx> ClosureSubsts<'tcx> {
236 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
237 /// for the closure parent, alongside additional closure-specific components.
240 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
241 ) -> ClosureSubsts<'tcx> {
243 substs: tcx.mk_substs(
244 parts.parent_substs.iter().copied().chain(
245 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
247 .map(|&ty| ty.into()),
253 /// Divides the closure substs into their respective components.
254 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
255 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
256 match self.substs[..] {
258 ref parent_substs @ ..,
260 closure_sig_as_fn_ptr_ty,
262 ] => ClosureSubstsParts {
265 closure_sig_as_fn_ptr_ty,
268 _ => bug!("closure substs missing synthetics"),
272 /// Returns `true` only if enough of the synthetic types are known to
273 /// allow using all of the methods on `ClosureSubsts` without panicking.
275 /// Used primarily by `ty::print::pretty` to be able to handle closure
276 /// types that haven't had their synthetic types substituted in.
277 pub fn is_valid(self) -> bool {
278 self.substs.len() >= 3
279 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
282 /// Returns the substitutions of the closure's parent.
283 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
284 self.split().parent_substs
287 /// Returns an iterator over the list of types of captured paths by the closure.
288 /// In case there was a type error in figuring out the types of the captured path, an
289 /// empty iterator is returned.
291 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
292 match self.tupled_upvars_ty().kind() {
293 TyKind::Error(_) => None,
294 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
295 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
296 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
302 /// Returns the tuple type representing the upvars for this closure.
304 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
305 self.split().tupled_upvars_ty.expect_ty()
308 /// Returns the closure kind for this closure; may return a type
309 /// variable during inference. To get the closure kind during
310 /// inference, use `infcx.closure_kind(substs)`.
311 pub fn kind_ty(self) -> Ty<'tcx> {
312 self.split().closure_kind_ty.expect_ty()
315 /// Returns the `fn` pointer type representing the closure signature for this
317 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
318 // type is known at the time of the creation of `ClosureSubsts`,
319 // see `rustc_hir_analysis::check::closure`.
320 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
321 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
324 /// Returns the closure kind for this closure; only usable outside
325 /// of an inference context, because in that context we know that
326 /// there are no type variables.
328 /// If you have an inference context, use `infcx.closure_kind()`.
329 pub fn kind(self) -> ty::ClosureKind {
330 self.kind_ty().to_opt_closure_kind().unwrap()
333 /// Extracts the signature from the closure.
334 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
335 let ty = self.sig_as_fn_ptr_ty();
337 ty::FnPtr(sig) => *sig,
338 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
342 pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
343 ty::print::PrintClosureAsImpl { closure: self }
347 /// Similar to `ClosureSubsts`; see the above documentation for more.
348 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
349 pub struct GeneratorSubsts<'tcx> {
350 pub substs: SubstsRef<'tcx>,
353 pub struct GeneratorSubstsParts<'tcx, T> {
354 pub parent_substs: &'tcx [GenericArg<'tcx>],
359 pub tupled_upvars_ty: T,
362 impl<'tcx> GeneratorSubsts<'tcx> {
363 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
364 /// for the generator parent, alongside additional generator-specific components.
367 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
368 ) -> GeneratorSubsts<'tcx> {
370 substs: tcx.mk_substs(
371 parts.parent_substs.iter().copied().chain(
377 parts.tupled_upvars_ty,
380 .map(|&ty| ty.into()),
386 /// Divides the generator substs into their respective components.
387 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
388 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
389 match self.substs[..] {
390 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
391 GeneratorSubstsParts {
400 _ => bug!("generator substs missing synthetics"),
404 /// Returns `true` only if enough of the synthetic types are known to
405 /// allow using all of the methods on `GeneratorSubsts` without panicking.
407 /// Used primarily by `ty::print::pretty` to be able to handle generator
408 /// types that haven't had their synthetic types substituted in.
409 pub fn is_valid(self) -> bool {
410 self.substs.len() >= 5
411 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
414 /// Returns the substitutions of the generator's parent.
415 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
416 self.split().parent_substs
419 /// This describes the types that can be contained in a generator.
420 /// It will be a type variable initially and unified in the last stages of typeck of a body.
421 /// It contains a tuple of all the types that could end up on a generator frame.
422 /// The state transformation MIR pass may only produce layouts which mention types
423 /// in this tuple. Upvars are not counted here.
424 pub fn witness(self) -> Ty<'tcx> {
425 self.split().witness.expect_ty()
428 /// Returns an iterator over the list of types of captured paths by the generator.
429 /// In case there was a type error in figuring out the types of the captured path, an
430 /// empty iterator is returned.
432 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
433 match self.tupled_upvars_ty().kind() {
434 TyKind::Error(_) => None,
435 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
436 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
437 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
443 /// Returns the tuple type representing the upvars for this generator.
445 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
446 self.split().tupled_upvars_ty.expect_ty()
449 /// Returns the type representing the resume type of the generator.
450 pub fn resume_ty(self) -> Ty<'tcx> {
451 self.split().resume_ty.expect_ty()
454 /// Returns the type representing the yield type of the generator.
455 pub fn yield_ty(self) -> Ty<'tcx> {
456 self.split().yield_ty.expect_ty()
459 /// Returns the type representing the return type of the generator.
460 pub fn return_ty(self) -> Ty<'tcx> {
461 self.split().return_ty.expect_ty()
464 /// Returns the "generator signature", which consists of its yield
465 /// and return types.
467 /// N.B., some bits of the code prefers to see this wrapped in a
468 /// binder, but it never contains bound regions. Probably this
469 /// function should be removed.
470 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
471 ty::Binder::dummy(self.sig())
474 /// Returns the "generator signature", which consists of its resume, yield
475 /// and return types.
476 pub fn sig(self) -> GenSig<'tcx> {
478 resume_ty: self.resume_ty(),
479 yield_ty: self.yield_ty(),
480 return_ty: self.return_ty(),
485 impl<'tcx> GeneratorSubsts<'tcx> {
486 /// Generator has not been resumed yet.
487 pub const UNRESUMED: usize = 0;
488 /// Generator has returned or is completed.
489 pub const RETURNED: usize = 1;
490 /// Generator has been poisoned.
491 pub const POISONED: usize = 2;
493 const UNRESUMED_NAME: &'static str = "Unresumed";
494 const RETURNED_NAME: &'static str = "Returned";
495 const POISONED_NAME: &'static str = "Panicked";
497 /// The valid variant indices of this generator.
499 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
500 // FIXME requires optimized MIR
501 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
502 VariantIdx::new(0)..VariantIdx::new(num_variants)
505 /// The discriminant for the given variant. Panics if the `variant_index` is
508 pub fn discriminant_for_variant(
512 variant_index: VariantIdx,
514 // Generators don't support explicit discriminant values, so they are
515 // the same as the variant index.
516 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
517 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
520 /// The set of all discriminants for the generator, enumerated with their
523 pub fn discriminants(
527 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
528 self.variant_range(def_id, tcx).map(move |index| {
529 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
533 /// Calls `f` with a reference to the name of the enumerator for the given
535 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
537 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
538 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
539 Self::POISONED => Cow::from(Self::POISONED_NAME),
540 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
544 /// The type of the state discriminant used in the generator type.
546 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
550 /// This returns the types of the MIR locals which had to be stored across suspension points.
551 /// It is calculated in rustc_mir_transform::generator::StateTransform.
552 /// All the types here must be in the tuple in GeneratorInterior.
554 /// The locals are grouped by their variant number. Note that some locals may
555 /// be repeated in multiple variants.
561 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
562 let layout = tcx.generator_layout(def_id).unwrap();
563 layout.variant_fields.iter().map(move |variant| {
566 .map(move |field| ty::EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
570 /// This is the types of the fields of a generator which are not stored in a
573 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
578 #[derive(Debug, Copy, Clone, HashStable)]
579 pub enum UpvarSubsts<'tcx> {
580 Closure(SubstsRef<'tcx>),
581 Generator(SubstsRef<'tcx>),
584 impl<'tcx> UpvarSubsts<'tcx> {
585 /// Returns an iterator over the list of types of captured paths by the closure/generator.
586 /// In case there was a type error in figuring out the types of the captured path, an
587 /// empty iterator is returned.
589 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
590 let tupled_tys = match self {
591 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
592 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
595 match tupled_tys.kind() {
596 TyKind::Error(_) => None,
597 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
598 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
599 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
606 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
608 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
609 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
614 /// An inline const is modeled like
615 /// ```ignore (illustrative)
616 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
620 /// - 'l0...'li and T0...Tj are the generic parameters
621 /// inherited from the item that defined the inline const,
622 /// - R represents the type of the constant.
624 /// When the inline const is instantiated, `R` is substituted as the actual inferred
625 /// type of the constant. The reason that `R` is represented as an extra type parameter
626 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
627 /// inline const can reference lifetimes that are internal to the creating function.
628 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
629 pub struct InlineConstSubsts<'tcx> {
630 /// Generic parameters from the enclosing item,
631 /// concatenated with the inferred type of the constant.
632 pub substs: SubstsRef<'tcx>,
635 /// Struct returned by `split()`.
636 pub struct InlineConstSubstsParts<'tcx, T> {
637 pub parent_substs: &'tcx [GenericArg<'tcx>],
641 impl<'tcx> InlineConstSubsts<'tcx> {
642 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
645 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
646 ) -> InlineConstSubsts<'tcx> {
648 substs: tcx.mk_substs(
649 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
654 /// Divides the inline const substs into their respective components.
655 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
656 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
657 match self.substs[..] {
658 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
659 _ => bug!("inline const substs missing synthetics"),
663 /// Returns the substitutions of the inline const's parent.
664 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
665 self.split().parent_substs
668 /// Returns the type of this inline const.
669 pub fn ty(self) -> Ty<'tcx> {
670 self.split().ty.expect_ty()
674 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
675 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
676 pub enum ExistentialPredicate<'tcx> {
677 /// E.g., `Iterator`.
678 Trait(ExistentialTraitRef<'tcx>),
679 /// E.g., `Iterator::Item = T`.
680 Projection(ExistentialProjection<'tcx>),
685 impl<'tcx> ExistentialPredicate<'tcx> {
686 /// Compares via an ordering that will not change if modules are reordered or other changes are
687 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
688 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
689 use self::ExistentialPredicate::*;
690 match (*self, *other) {
691 (Trait(_), Trait(_)) => Ordering::Equal,
692 (Projection(ref a), Projection(ref b)) => {
693 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
695 (AutoTrait(ref a), AutoTrait(ref b)) => {
696 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
698 (Trait(_), _) => Ordering::Less,
699 (Projection(_), Trait(_)) => Ordering::Greater,
700 (Projection(_), _) => Ordering::Less,
701 (AutoTrait(_), _) => Ordering::Greater,
706 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
707 /// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
708 /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
709 /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
710 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
711 use crate::ty::ToPredicate;
712 match self.skip_binder() {
713 ExistentialPredicate::Trait(tr) => {
714 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
716 ExistentialPredicate::Projection(p) => {
717 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
719 ExistentialPredicate::AutoTrait(did) => {
720 let trait_ref = self.rebind(ty::TraitRef {
722 substs: tcx.mk_substs_trait(self_ty, &[]),
724 trait_ref.without_const().to_predicate(tcx)
730 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'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 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
816 /// are the parameters defined on trait.
817 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
818 ty::Binder::dummy(TraitRef {
820 substs: InternalSubsts::identity_for_item(tcx, def_id),
825 pub fn self_ty(&self) -> Ty<'tcx> {
826 self.substs.type_at(0)
832 substs: SubstsRef<'tcx>,
833 ) -> ty::TraitRef<'tcx> {
834 let defs = tcx.generics_of(trait_id);
835 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
839 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
841 impl<'tcx> PolyTraitRef<'tcx> {
842 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
843 self.map_bound_ref(|tr| tr.self_ty())
846 pub fn def_id(&self) -> DefId {
847 self.skip_binder().def_id
850 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
851 self.map_bound(|trait_ref| ty::TraitPredicate {
853 constness: ty::BoundConstness::NotConst,
854 polarity: ty::ImplPolarity::Positive,
858 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
859 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
860 self.map_bound(|trait_ref| ty::TraitPredicate {
862 constness: ty::BoundConstness::NotConst,
863 polarity: ty::ImplPolarity::Negative,
868 impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
869 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
870 self.to_string().into_diagnostic_arg()
874 /// An existential reference to a trait, where `Self` is erased.
875 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
876 /// ```ignore (illustrative)
877 /// exists T. T: Trait<'a, 'b, X, Y>
879 /// The substitutions don't include the erased `Self`, only trait
880 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
881 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
882 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
883 pub struct ExistentialTraitRef<'tcx> {
885 pub substs: SubstsRef<'tcx>,
888 impl<'tcx> ExistentialTraitRef<'tcx> {
889 pub fn erase_self_ty(
891 trait_ref: ty::TraitRef<'tcx>,
892 ) -> ty::ExistentialTraitRef<'tcx> {
893 // Assert there is a Self.
894 trait_ref.substs.type_at(0);
896 ty::ExistentialTraitRef {
897 def_id: trait_ref.def_id,
898 substs: tcx.intern_substs(&trait_ref.substs[1..]),
902 /// Object types don't have a self type specified. Therefore, when
903 /// we convert the principal trait-ref into a normal trait-ref,
904 /// you must give *some* self type. A common choice is `mk_err()`
905 /// or some placeholder type.
906 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
907 // otherwise the escaping vars would be captured by the binder
908 // debug_assert!(!self_ty.has_escaping_bound_vars());
910 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
914 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
916 impl<'tcx> PolyExistentialTraitRef<'tcx> {
917 pub fn def_id(&self) -> DefId {
918 self.skip_binder().def_id
921 /// Object types don't have a self type specified. Therefore, when
922 /// we convert the principal trait-ref into a normal trait-ref,
923 /// you must give *some* self type. A common choice is `mk_err()`
924 /// or some placeholder type.
925 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
926 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
930 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
931 #[derive(HashStable)]
932 pub enum BoundVariableKind {
934 Region(BoundRegionKind),
938 impl BoundVariableKind {
939 pub fn expect_region(self) -> BoundRegionKind {
941 BoundVariableKind::Region(lt) => lt,
942 _ => bug!("expected a region, but found another kind"),
946 pub fn expect_ty(self) -> BoundTyKind {
948 BoundVariableKind::Ty(ty) => ty,
949 _ => bug!("expected a type, but found another kind"),
953 pub fn expect_const(self) {
955 BoundVariableKind::Const => (),
956 _ => bug!("expected a const, but found another kind"),
961 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
962 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
963 /// (which would be represented by the type `PolyTraitRef ==
964 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
965 /// erase, or otherwise "discharge" these bound vars, we change the
966 /// type from `Binder<'tcx, T>` to just `T` (see
967 /// e.g., `liberate_late_bound_regions`).
969 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
970 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
971 #[derive(HashStable, Lift)]
972 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
974 impl<'tcx, T> Binder<'tcx, T>
976 T: TypeVisitable<'tcx>,
978 /// Wraps `value` in a binder, asserting that `value` does not
979 /// contain any bound vars that would be bound by the
980 /// binder. This is commonly used to 'inject' a value T into a
981 /// different binding level.
982 pub fn dummy(value: T) -> Binder<'tcx, T> {
983 assert!(!value.has_escaping_bound_vars());
984 Binder(value, ty::List::empty())
987 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
988 if cfg!(debug_assertions) {
989 let mut validator = ValidateBoundVars::new(vars);
990 value.visit_with(&mut validator);
996 impl<'tcx, T> Binder<'tcx, T> {
997 /// Skips the binder and returns the "bound" value. This is a
998 /// risky thing to do because it's easy to get confused about
999 /// De Bruijn indices and the like. It is usually better to
1000 /// discharge the binder using `no_bound_vars` or
1001 /// `replace_late_bound_regions` or something like
1002 /// that. `skip_binder` is only valid when you are either
1003 /// extracting data that has nothing to do with bound vars, you
1004 /// are doing some sort of test that does not involve bound
1005 /// regions, or you are being very careful about your depth
1008 /// Some examples where `skip_binder` is reasonable:
1010 /// - extracting the `DefId` from a PolyTraitRef;
1011 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1012 /// a type parameter `X`, since the type `X` does not reference any regions
1013 pub fn skip_binder(self) -> T {
1017 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1021 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1022 Binder(&self.0, self.1)
1025 pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
1029 Binder(&self.0, self.1)
1032 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1036 let value = f(&self.0);
1037 Binder(value, self.1)
1040 pub fn map_bound_ref<F, U: TypeVisitable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1044 self.as_ref().map_bound(f)
1047 pub fn map_bound<F, U: TypeVisitable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1051 let value = f(self.0);
1052 if cfg!(debug_assertions) {
1053 let mut validator = ValidateBoundVars::new(self.1);
1054 value.visit_with(&mut validator);
1056 Binder(value, self.1)
1059 pub fn try_map_bound<F, U: TypeVisitable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1061 F: FnOnce(T) -> Result<U, E>,
1063 let value = f(self.0)?;
1064 if cfg!(debug_assertions) {
1065 let mut validator = ValidateBoundVars::new(self.1);
1066 value.visit_with(&mut validator);
1068 Ok(Binder(value, self.1))
1071 /// Wraps a `value` in a binder, using the same bound variables as the
1072 /// current `Binder`. This should not be used if the new value *changes*
1073 /// the bound variables. Note: the (old or new) value itself does not
1074 /// necessarily need to *name* all the bound variables.
1076 /// This currently doesn't do anything different than `bind`, because we
1077 /// don't actually track bound vars. However, semantically, it is different
1078 /// because bound vars aren't allowed to change here, whereas they are
1079 /// in `bind`. This may be (debug) asserted in the future.
1080 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1082 U: TypeVisitable<'tcx>,
1084 if cfg!(debug_assertions) {
1085 let mut validator = ValidateBoundVars::new(self.bound_vars());
1086 value.visit_with(&mut validator);
1088 Binder(value, self.1)
1091 /// Unwraps and returns the value within, but only if it contains
1092 /// no bound vars at all. (In other words, if this binder --
1093 /// and indeed any enclosing binder -- doesn't bind anything at
1094 /// all.) Otherwise, returns `None`.
1096 /// (One could imagine having a method that just unwraps a single
1097 /// binder, but permits late-bound vars bound by enclosing
1098 /// binders, but that would require adjusting the debruijn
1099 /// indices, and given the shallow binding structure we often use,
1100 /// would not be that useful.)
1101 pub fn no_bound_vars(self) -> Option<T>
1103 T: TypeVisitable<'tcx>,
1105 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1108 /// Splits the contents into two things that share the same binder
1109 /// level as the original, returning two distinct binders.
1111 /// `f` should consider bound regions at depth 1 to be free, and
1112 /// anything it produces with bound regions at depth 1 will be
1113 /// bound in the resulting return values.
1114 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1116 F: FnOnce(T) -> (U, V),
1118 let (u, v) = f(self.0);
1119 (Binder(u, self.1), Binder(v, self.1))
1123 impl<'tcx, T> Binder<'tcx, Option<T>> {
1124 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1125 let bound_vars = self.1;
1126 self.0.map(|v| Binder(v, bound_vars))
1130 /// Represents the projection of an associated type. In explicit UFCS
1131 /// form this would be written `<T as Trait<..>>::N`.
1132 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1133 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1134 pub struct ProjectionTy<'tcx> {
1135 /// The parameters of the associated item.
1136 pub substs: SubstsRef<'tcx>,
1138 /// The `DefId` of the `TraitItem` for the associated type `N`.
1140 /// Note that this is not the `DefId` of the `TraitRef` containing this
1141 /// associated type, which is in `tcx.associated_item(item_def_id).container`,
1142 /// aka. `tcx.parent(item_def_id).unwrap()`.
1143 pub item_def_id: DefId,
1146 impl<'tcx> ProjectionTy<'tcx> {
1147 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1148 match tcx.def_kind(self.item_def_id) {
1149 DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.item_def_id),
1150 DefKind::ImplTraitPlaceholder => {
1151 tcx.parent(tcx.impl_trait_in_trait_parent(self.item_def_id))
1153 kind => bug!("unexpected DefKind in ProjectionTy: {kind:?}"),
1157 /// Extracts the underlying trait reference and own substs from this projection.
1158 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1159 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1160 pub fn trait_ref_and_own_substs(
1163 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1164 let def_id = tcx.parent(self.item_def_id);
1165 assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
1166 let trait_generics = tcx.generics_of(def_id);
1168 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1169 &self.substs[trait_generics.count()..],
1173 /// Extracts the underlying trait reference from this projection.
1174 /// For example, if this is a projection of `<T as Iterator>::Item`,
1175 /// then this function would return a `T: Iterator` trait reference.
1177 /// WARNING: This will drop the substs for generic associated types
1178 /// consider calling [Self::trait_ref_and_own_substs] to get those
1180 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1181 let def_id = self.trait_def_id(tcx);
1182 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1185 pub fn self_ty(&self) -> Ty<'tcx> {
1186 self.substs.type_at(0)
1190 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
1191 pub struct GenSig<'tcx> {
1192 pub resume_ty: Ty<'tcx>,
1193 pub yield_ty: Ty<'tcx>,
1194 pub return_ty: Ty<'tcx>,
1197 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1199 /// Signature of a function type, which we have arbitrarily
1200 /// decided to use to refer to the input/output types.
1202 /// - `inputs`: is the list of arguments and their modes.
1203 /// - `output`: is the return type.
1204 /// - `c_variadic`: indicates whether this is a C-variadic function.
1205 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1206 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1207 pub struct FnSig<'tcx> {
1208 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1209 pub c_variadic: bool,
1210 pub unsafety: hir::Unsafety,
1214 impl<'tcx> FnSig<'tcx> {
1215 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1216 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1219 pub fn output(&self) -> Ty<'tcx> {
1220 self.inputs_and_output[self.inputs_and_output.len() - 1]
1223 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1225 fn fake() -> FnSig<'tcx> {
1227 inputs_and_output: List::empty(),
1229 unsafety: hir::Unsafety::Normal,
1230 abi: abi::Abi::Rust,
1235 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1237 impl<'tcx> PolyFnSig<'tcx> {
1239 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1240 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1243 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1244 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1246 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1247 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1250 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1251 self.map_bound_ref(|fn_sig| fn_sig.output())
1253 pub fn c_variadic(&self) -> bool {
1254 self.skip_binder().c_variadic
1256 pub fn unsafety(&self) -> hir::Unsafety {
1257 self.skip_binder().unsafety
1259 pub fn abi(&self) -> abi::Abi {
1260 self.skip_binder().abi
1264 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1266 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1267 #[derive(HashStable)]
1268 pub struct ParamTy {
1273 impl<'tcx> ParamTy {
1274 pub fn new(index: u32, name: Symbol) -> ParamTy {
1275 ParamTy { index, name }
1278 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1279 ParamTy::new(def.index, def.name)
1283 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1284 tcx.mk_ty_param(self.index, self.name)
1287 pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
1288 let generics = tcx.generics_of(item_with_generics);
1289 let type_param = generics.type_param(self, tcx);
1290 tcx.def_span(type_param.def_id)
1294 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1295 #[derive(HashStable)]
1296 pub struct ParamConst {
1302 pub fn new(index: u32, name: Symbol) -> ParamConst {
1303 ParamConst { index, name }
1306 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1307 ParamConst::new(def.index, def.name)
1311 /// Use this rather than `RegionKind`, whenever possible.
1312 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1313 #[rustc_pass_by_value]
1314 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
1316 impl<'tcx> Deref for Region<'tcx> {
1317 type Target = RegionKind<'tcx>;
1320 fn deref(&self) -> &RegionKind<'tcx> {
1325 impl<'tcx> fmt::Debug for Region<'tcx> {
1326 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1327 write!(f, "{:?}", self.kind())
1331 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1332 #[derive(HashStable)]
1333 pub struct EarlyBoundRegion {
1339 impl fmt::Debug for EarlyBoundRegion {
1340 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1341 write!(f, "{}, {}", self.index, self.name)
1345 /// A **`const`** **v**ariable **ID**.
1346 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1347 #[derive(HashStable, TyEncodable, TyDecodable)]
1348 pub struct ConstVid<'tcx> {
1350 pub phantom: PhantomData<&'tcx ()>,
1353 rustc_index::newtype_index! {
1354 /// A **region** (lifetime) **v**ariable **ID**.
1355 #[derive(HashStable)]
1356 pub struct RegionVid {
1357 DEBUG_FORMAT = custom,
1361 impl Atom for RegionVid {
1362 fn index(self) -> usize {
1367 rustc_index::newtype_index! {
1368 #[derive(HashStable)]
1369 pub struct BoundVar { .. }
1372 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1373 #[derive(HashStable)]
1374 pub struct BoundTy {
1376 pub kind: BoundTyKind,
1379 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1380 #[derive(HashStable)]
1381 pub enum BoundTyKind {
1386 impl From<BoundVar> for BoundTy {
1387 fn from(var: BoundVar) -> Self {
1388 BoundTy { var, kind: BoundTyKind::Anon }
1392 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1393 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1394 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1395 pub struct ExistentialProjection<'tcx> {
1396 pub item_def_id: DefId,
1397 pub substs: SubstsRef<'tcx>,
1398 pub term: Term<'tcx>,
1401 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1403 impl<'tcx> ExistentialProjection<'tcx> {
1404 /// Extracts the underlying existential trait reference from this projection.
1405 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1406 /// then this function would return an `exists T. T: Iterator` existential trait
1408 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1409 let def_id = tcx.parent(self.item_def_id);
1410 let subst_count = tcx.generics_of(def_id).count() - 1;
1411 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1412 ty::ExistentialTraitRef { def_id, substs }
1415 pub fn with_self_ty(
1419 ) -> ty::ProjectionPredicate<'tcx> {
1420 // otherwise the escaping regions would be captured by the binders
1421 debug_assert!(!self_ty.has_escaping_bound_vars());
1423 ty::ProjectionPredicate {
1424 projection_ty: ty::ProjectionTy {
1425 item_def_id: self.item_def_id,
1426 substs: tcx.mk_substs_trait(self_ty, self.substs),
1432 pub fn erase_self_ty(
1434 projection_predicate: ty::ProjectionPredicate<'tcx>,
1436 // Assert there is a Self.
1437 projection_predicate.projection_ty.substs.type_at(0);
1440 item_def_id: projection_predicate.projection_ty.item_def_id,
1441 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1442 term: projection_predicate.term,
1447 impl<'tcx> PolyExistentialProjection<'tcx> {
1448 pub fn with_self_ty(
1452 ) -> ty::PolyProjectionPredicate<'tcx> {
1453 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1456 pub fn item_def_id(&self) -> DefId {
1457 self.skip_binder().item_def_id
1461 /// Region utilities
1462 impl<'tcx> Region<'tcx> {
1463 pub fn kind(self) -> RegionKind<'tcx> {
1467 pub fn get_name(self) -> Option<Symbol> {
1468 if self.has_name() {
1469 let name = match *self {
1470 ty::ReEarlyBound(ebr) => Some(ebr.name),
1471 ty::ReLateBound(_, br) => br.kind.get_name(),
1472 ty::ReFree(fr) => fr.bound_region.get_name(),
1473 ty::ReStatic => Some(kw::StaticLifetime),
1474 ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
1484 /// Is this region named by the user?
1485 pub fn has_name(self) -> bool {
1487 ty::ReEarlyBound(ebr) => ebr.has_name(),
1488 ty::ReLateBound(_, br) => br.kind.is_named(),
1489 ty::ReFree(fr) => fr.bound_region.is_named(),
1490 ty::ReStatic => true,
1491 ty::ReVar(..) => false,
1492 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1493 ty::ReErased => false,
1498 pub fn is_static(self) -> bool {
1499 matches!(*self, ty::ReStatic)
1503 pub fn is_erased(self) -> bool {
1504 matches!(*self, ty::ReErased)
1508 pub fn is_late_bound(self) -> bool {
1509 matches!(*self, ty::ReLateBound(..))
1513 pub fn is_placeholder(self) -> bool {
1514 matches!(*self, ty::RePlaceholder(..))
1518 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1520 ty::ReLateBound(debruijn, _) => debruijn >= index,
1525 pub fn type_flags(self) -> TypeFlags {
1526 let mut flags = TypeFlags::empty();
1530 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1531 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1532 flags = flags | TypeFlags::HAS_RE_INFER;
1534 ty::RePlaceholder(..) => {
1535 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1536 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1537 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1539 ty::ReEarlyBound(..) => {
1540 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1541 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1542 flags = flags | TypeFlags::HAS_RE_PARAM;
1544 ty::ReFree { .. } => {
1545 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1546 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1549 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1551 ty::ReLateBound(..) => {
1552 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1555 flags = flags | TypeFlags::HAS_RE_ERASED;
1559 debug!("type_flags({:?}) = {:?}", self, flags);
1564 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1565 /// For example, consider the regions in this snippet of code:
1567 /// ```ignore (illustrative)
1569 /// // ^^ -- early bound, declared on an impl
1571 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1572 /// // ^^ ^^ ^ anonymous, late-bound
1573 /// // | early-bound, appears in where-clauses
1574 /// // late-bound, appears only in fn args
1579 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1580 /// of the impl, and for all the other highlighted regions, it
1581 /// would return the `DefId` of the function. In other cases (not shown), this
1582 /// function might return the `DefId` of a closure.
1583 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1585 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1586 ty::ReFree(fr) => fr.scope,
1587 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1591 /// True for free regions other than `'static`.
1592 pub fn is_free(self) -> bool {
1593 matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
1596 /// True if `self` is a free region or static.
1597 pub fn is_free_or_static(self) -> bool {
1599 ty::ReStatic => true,
1600 _ => self.is_free(),
1604 pub fn is_var(self) -> bool {
1605 matches!(self.kind(), ty::ReVar(_))
1610 impl<'tcx> Ty<'tcx> {
1612 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1617 pub fn flags(self) -> TypeFlags {
1622 pub fn is_unit(self) -> bool {
1624 Tuple(ref tys) => tys.is_empty(),
1630 pub fn is_never(self) -> bool {
1631 matches!(self.kind(), Never)
1635 pub fn is_primitive(self) -> bool {
1636 self.kind().is_primitive()
1640 pub fn is_adt(self) -> bool {
1641 matches!(self.kind(), Adt(..))
1645 pub fn is_ref(self) -> bool {
1646 matches!(self.kind(), Ref(..))
1650 pub fn is_ty_var(self) -> bool {
1651 matches!(self.kind(), Infer(TyVar(_)))
1655 pub fn ty_vid(self) -> Option<ty::TyVid> {
1657 &Infer(TyVar(vid)) => Some(vid),
1663 pub fn is_ty_infer(self) -> bool {
1664 matches!(self.kind(), Infer(_))
1668 pub fn is_phantom_data(self) -> bool {
1669 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1673 pub fn is_bool(self) -> bool {
1674 *self.kind() == Bool
1677 /// Returns `true` if this type is a `str`.
1679 pub fn is_str(self) -> bool {
1684 pub fn is_param(self, index: u32) -> bool {
1686 ty::Param(ref data) => data.index == index,
1692 pub fn is_slice(self) -> bool {
1693 matches!(self.kind(), Slice(_))
1697 pub fn is_array_slice(self) -> bool {
1700 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1706 pub fn is_array(self) -> bool {
1707 matches!(self.kind(), Array(..))
1711 pub fn is_simd(self) -> bool {
1713 Adt(def, _) => def.repr().simd(),
1718 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1720 Array(ty, _) | Slice(ty) => *ty,
1721 Str => tcx.types.u8,
1722 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1726 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1728 Adt(def, substs) => {
1729 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1730 let variant = def.non_enum_variant();
1731 let f0_ty = variant.fields[0].ty(tcx, substs);
1733 match f0_ty.kind() {
1734 // If the first field is an array, we assume it is the only field and its
1735 // elements are the SIMD components.
1736 Array(f0_elem_ty, f0_len) => {
1737 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1738 // The way we evaluate the `N` in `[T; N]` here only works since we use
1739 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1740 // if we use it in generic code. See the `simd-array-trait` ui test.
1741 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1743 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1744 // all have the same type).
1745 _ => (variant.fields.len() as u64, f0_ty),
1748 _ => bug!("`simd_size_and_type` called on invalid type"),
1753 pub fn is_region_ptr(self) -> bool {
1754 matches!(self.kind(), Ref(..))
1758 pub fn is_mutable_ptr(self) -> bool {
1761 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1762 | Ref(_, _, hir::Mutability::Mut)
1766 /// Get the mutability of the reference or `None` when not a reference
1768 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1770 Ref(_, _, mutability) => Some(*mutability),
1776 pub fn is_unsafe_ptr(self) -> bool {
1777 matches!(self.kind(), RawPtr(_))
1780 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1782 pub fn is_any_ptr(self) -> bool {
1783 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1787 pub fn is_box(self) -> bool {
1789 Adt(def, _) => def.is_box(),
1794 /// Panics if called on any type other than `Box<T>`.
1795 pub fn boxed_ty(self) -> Ty<'tcx> {
1797 Adt(def, substs) if def.is_box() => substs.type_at(0),
1798 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1802 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1803 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1804 /// contents are abstract to rustc.)
1806 pub fn is_scalar(self) -> bool {
1816 | Infer(IntVar(_) | FloatVar(_))
1820 /// Returns `true` if this type is a floating point type.
1822 pub fn is_floating_point(self) -> bool {
1823 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1827 pub fn is_trait(self) -> bool {
1828 matches!(self.kind(), Dynamic(_, _, ty::Dyn))
1832 pub fn is_dyn_star(self) -> bool {
1833 matches!(self.kind(), Dynamic(_, _, ty::DynStar))
1837 pub fn is_enum(self) -> bool {
1838 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1842 pub fn is_union(self) -> bool {
1843 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1847 pub fn is_closure(self) -> bool {
1848 matches!(self.kind(), Closure(..))
1852 pub fn is_generator(self) -> bool {
1853 matches!(self.kind(), Generator(..))
1857 pub fn is_integral(self) -> bool {
1858 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
1862 pub fn is_fresh_ty(self) -> bool {
1863 matches!(self.kind(), Infer(FreshTy(_)))
1867 pub fn is_fresh(self) -> bool {
1868 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
1872 pub fn is_char(self) -> bool {
1873 matches!(self.kind(), Char)
1877 pub fn is_numeric(self) -> bool {
1878 self.is_integral() || self.is_floating_point()
1882 pub fn is_signed(self) -> bool {
1883 matches!(self.kind(), Int(_))
1887 pub fn is_ptr_sized_integral(self) -> bool {
1888 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
1892 pub fn has_concrete_skeleton(self) -> bool {
1893 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
1896 /// Checks whether a type recursively contains another type
1898 /// Example: `Option<()>` contains `()`
1899 pub fn contains(self, other: Ty<'tcx>) -> bool {
1900 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
1902 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
1905 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1906 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
1910 let cf = self.visit_with(&mut ContainsTyVisitor(other));
1914 /// Returns the type and mutability of `*ty`.
1916 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1917 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1918 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1920 Adt(def, _) if def.is_box() => {
1921 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
1923 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
1924 RawPtr(mt) if explicit => Some(*mt),
1929 /// Returns the type of `ty[i]`.
1930 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
1932 Array(ty, _) | Slice(ty) => Some(*ty),
1937 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
1939 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
1942 // ignore errors (#54954)
1943 ty::Binder::dummy(FnSig::fake())
1945 Closure(..) => bug!(
1946 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1948 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
1953 pub fn is_fn(self) -> bool {
1954 matches!(self.kind(), FnDef(..) | FnPtr(_))
1958 pub fn is_fn_ptr(self) -> bool {
1959 matches!(self.kind(), FnPtr(_))
1963 pub fn is_impl_trait(self) -> bool {
1964 matches!(self.kind(), Opaque(..))
1968 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
1970 Adt(adt, _) => Some(*adt),
1975 /// Iterates over tuple fields.
1976 /// Panics when called on anything but a tuple.
1978 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
1980 Tuple(substs) => substs,
1981 _ => bug!("tuple_fields called on non-tuple"),
1985 /// If the type contains variants, returns the valid range of variant indices.
1987 // FIXME: This requires the optimized MIR in the case of generators.
1989 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
1991 TyKind::Adt(adt, _) => Some(adt.variant_range()),
1992 TyKind::Generator(def_id, substs, _) => {
1993 Some(substs.as_generator().variant_range(*def_id, tcx))
1999 /// If the type contains variants, returns the variant for `variant_index`.
2000 /// Panics if `variant_index` is out of range.
2002 // FIXME: This requires the optimized MIR in the case of generators.
2004 pub fn discriminant_for_variant(
2007 variant_index: VariantIdx,
2008 ) -> Option<Discr<'tcx>> {
2010 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2011 // This can actually happen during CTFE, see
2012 // https://github.com/rust-lang/rust/issues/89765.
2015 TyKind::Adt(adt, _) if adt.is_enum() => {
2016 Some(adt.discriminant_for_variant(tcx, variant_index))
2018 TyKind::Generator(def_id, substs, _) => {
2019 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2025 /// Returns the type of the discriminant of this type.
2026 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2028 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2029 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2031 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2032 let assoc_items = tcx.associated_item_def_ids(
2033 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2035 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2054 | ty::GeneratorWitness(..)
2058 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2061 | ty::Placeholder(_)
2062 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2063 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2068 /// Returns the type of metadata for (potentially fat) pointers to this type,
2069 /// and a boolean signifying if this is conditional on this type being `Sized`.
2070 pub fn ptr_metadata_ty(
2073 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2074 ) -> (Ty<'tcx>, bool) {
2075 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2078 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2089 | ty::GeneratorWitness(..)
2094 // Extern types have metadata = ().
2096 // If returned by `struct_tail_without_normalization` this is a unit struct
2097 // without any fields, or not a struct, and therefore is Sized.
2099 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2100 // a.k.a. unit type, which is Sized
2101 | ty::Tuple(..) => (tcx.types.unit, false),
2103 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2104 ty::Dynamic(..) => {
2105 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2106 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2109 // type parameters only have unit metadata if they're sized, so return true
2110 // to make sure we double check this during confirmation
2111 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2113 ty::Infer(ty::TyVar(_))
2115 | ty::Placeholder(..)
2116 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2117 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2122 /// When we create a closure, we record its kind (i.e., what trait
2123 /// it implements) into its `ClosureSubsts` using a type
2124 /// parameter. This is kind of a phantom type, except that the
2125 /// most convenient thing for us to are the integral types. This
2126 /// function converts such a special type into the closure
2127 /// kind. To go the other way, use
2128 /// `tcx.closure_kind_ty(closure_kind)`.
2130 /// Note that during type checking, we use an inference variable
2131 /// to represent the closure kind, because it has not yet been
2132 /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
2133 /// is complete, that type variable will be unified.
2134 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2136 Int(int_ty) => match int_ty {
2137 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2138 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2139 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2140 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2143 // "Bound" types appear in canonical queries when the
2144 // closure type is not yet known
2145 Bound(..) | Infer(_) => None,
2147 Error(_) => Some(ty::ClosureKind::Fn),
2149 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2153 /// Fast path helper for testing if a type is `Sized`.
2155 /// Returning true means the type is known to be sized. Returning
2156 /// `false` means nothing -- could be sized, might not be.
2158 /// Note that we could never rely on the fact that a type such as `[_]` is
2159 /// trivially `!Sized` because we could be in a type environment with a
2160 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2161 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2162 /// this method doesn't return `Option<bool>`.
2163 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2165 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2176 | ty::GeneratorWitness(..)
2180 | ty::Error(_) => true,
2182 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2184 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2186 ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(),
2188 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2190 ty::Infer(ty::TyVar(_)) => false,
2193 | ty::Placeholder(..)
2194 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2195 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2200 /// Fast path helper for primitives which are always `Copy` and which
2201 /// have a side-effect-free `Clone` impl.
2203 /// Returning true means the type is known to be pure and `Copy+Clone`.
2204 /// Returning `false` means nothing -- could be `Copy`, might not be.
2206 /// This is mostly useful for optimizations, as there are the types
2207 /// on which we can replace cloning with dereferencing.
2208 pub fn is_trivially_pure_clone_copy(self) -> bool {
2210 ty::Bool | ty::Char | ty::Never => true,
2212 // These aren't even `Clone`
2213 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2215 ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
2218 | ty::Float(..) => true,
2220 // The voldemort ZSTs are fine.
2221 ty::FnDef(..) => true,
2223 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2225 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2226 ty::Tuple(field_tys) => {
2227 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2230 // Sometimes traits aren't implemented for every ABI or arity,
2231 // because we can't be generic over everything yet.
2232 ty::FnPtr(..) => false,
2234 // Definitely absolutely not copy.
2235 ty::Ref(_, _, hir::Mutability::Mut) => false,
2237 // Thin pointers & thin shared references are pure-clone-copy, but for
2238 // anything with custom metadata it might be more complicated.
2239 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2241 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2243 // Might be, but not "trivial" so just giving the safe answer.
2244 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2246 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2248 ty::Bound(..) | ty::Placeholder(..) => {
2249 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2254 // If `self` is a primitive, return its [`Symbol`].
2255 pub fn primitive_symbol(self) -> Option<Symbol> {
2257 ty::Bool => Some(sym::bool),
2258 ty::Char => Some(sym::char),
2259 ty::Float(f) => match f {
2260 ty::FloatTy::F32 => Some(sym::f32),
2261 ty::FloatTy::F64 => Some(sym::f64),
2263 ty::Int(f) => match f {
2264 ty::IntTy::Isize => Some(sym::isize),
2265 ty::IntTy::I8 => Some(sym::i8),
2266 ty::IntTy::I16 => Some(sym::i16),
2267 ty::IntTy::I32 => Some(sym::i32),
2268 ty::IntTy::I64 => Some(sym::i64),
2269 ty::IntTy::I128 => Some(sym::i128),
2271 ty::Uint(f) => match f {
2272 ty::UintTy::Usize => Some(sym::usize),
2273 ty::UintTy::U8 => Some(sym::u8),
2274 ty::UintTy::U16 => Some(sym::u16),
2275 ty::UintTy::U32 => Some(sym::u32),
2276 ty::UintTy::U64 => Some(sym::u64),
2277 ty::UintTy::U128 => Some(sym::u128),
2284 /// Extra information about why we ended up with a particular variance.
2285 /// This is only used to add more information to error messages, and
2286 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2287 /// may lead to confusing notes in error messages, it will never cause
2288 /// a miscompilation or unsoundness.
2290 /// When in doubt, use `VarianceDiagInfo::default()`
2291 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2292 pub enum VarianceDiagInfo<'tcx> {
2293 /// No additional information - this is the default.
2294 /// We will not add any additional information to error messages.
2297 /// We switched our variance because a generic argument occurs inside
2298 /// the invariant generic argument of another type.
2300 /// The generic type containing the generic parameter
2301 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2303 /// The index of the generic parameter being used
2304 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2309 impl<'tcx> VarianceDiagInfo<'tcx> {
2310 /// Mirrors `Variance::xform` - used to 'combine' the existing
2311 /// and new `VarianceDiagInfo`s when our variance changes.
2312 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2313 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2315 VarianceDiagInfo::None => other,
2316 VarianceDiagInfo::Invariant { .. } => self,