1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
5 use crate::infer::canonical::Canonical;
6 use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
7 use crate::ty::visit::ValidateBoundVars;
8 use crate::ty::InferTy::*;
10 self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeSuperVisitable, TypeVisitable,
13 use crate::ty::{List, ParamEnv};
14 use hir::def::DefKind;
15 use polonius_engine::Atom;
16 use rustc_data_structures::captures::Captures;
17 use rustc_data_structures::intern::Interned;
19 use rustc_hir::def_id::DefId;
20 use rustc_hir::LangItem;
21 use rustc_index::vec::Idx;
22 use rustc_macros::HashStable;
23 use rustc_span::symbol::{kw, sym, Symbol};
25 use rustc_target::abi::VariantIdx;
26 use rustc_target::spec::abi;
28 use std::cmp::Ordering;
30 use std::marker::PhantomData;
31 use std::ops::{ControlFlow, Deref, Range};
32 use ty::util::IntTypeExt;
34 use rustc_type_ir::sty::TyKind::*;
35 use rustc_type_ir::RegionKind as IrRegionKind;
36 use rustc_type_ir::TyKind as IrTyKind;
38 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
39 #[rustc_diagnostic_item = "TyKind"]
40 pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
41 pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
43 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
44 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
45 pub struct TypeAndMut<'tcx> {
47 pub mutbl: hir::Mutability,
50 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
52 /// A "free" region `fr` can be interpreted as "some region
53 /// at least as big as the scope `fr.scope`".
54 pub struct FreeRegion {
56 pub bound_region: BoundRegionKind,
59 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
61 pub enum BoundRegionKind {
62 /// An anonymous region parameter for a given fn (&T)
63 BrAnon(u32, Option<Span>),
65 /// Named region parameters for functions (a in &'a T)
67 /// The `DefId` is needed to distinguish free regions in
68 /// the event of shadowing.
69 BrNamed(DefId, Symbol),
71 /// Anonymous region for the implicit env pointer parameter
76 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
78 pub struct BoundRegion {
80 pub kind: BoundRegionKind,
83 impl BoundRegionKind {
84 pub fn is_named(&self) -> bool {
86 BoundRegionKind::BrNamed(_, name) => {
87 name != kw::UnderscoreLifetime && name != kw::Empty
93 pub fn get_name(&self) -> Option<Symbol> {
96 BoundRegionKind::BrNamed(_, name) => return Some(name),
106 fn article(&self) -> &'static str;
109 impl<'tcx> Article for TyKind<'tcx> {
110 /// Get the article ("a" or "an") to use with this type.
111 fn article(&self) -> &'static str {
113 Int(_) | Float(_) | Array(_, _) => "an",
114 Adt(def, _) if def.is_enum() => "an",
115 // This should never happen, but ICEing and causing the user's code
116 // to not compile felt too harsh.
123 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
124 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
125 static_assert_size!(TyKind<'_>, 32);
127 /// A closure can be modeled as a struct that looks like:
128 /// ```ignore (illustrative)
129 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
133 /// - 'l0...'li and T0...Tj are the generic parameters
134 /// in scope on the function that defined the closure,
135 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
136 /// is rather hackily encoded via a scalar type. See
137 /// `Ty::to_opt_closure_kind` for details.
138 /// - CS represents the *closure signature*, representing as a `fn()`
139 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
140 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
142 /// - U is a type parameter representing the types of its upvars, tupled up
143 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
144 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
146 /// So, for example, given this function:
147 /// ```ignore (illustrative)
148 /// fn foo<'a, T>(data: &'a mut T) {
149 /// do(|| data.count += 1)
152 /// the type of the closure would be something like:
153 /// ```ignore (illustrative)
154 /// struct Closure<'a, T, U>(...U);
156 /// Note that the type of the upvar is not specified in the struct.
157 /// You may wonder how the impl would then be able to use the upvar,
158 /// if it doesn't know it's type? The answer is that the impl is
159 /// (conceptually) not fully generic over Closure but rather tied to
160 /// instances with the expected upvar types:
161 /// ```ignore (illustrative)
162 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
166 /// You can see that the *impl* fully specified the type of the upvar
167 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
168 /// (Here, I am assuming that `data` is mut-borrowed.)
170 /// Now, the last question you may ask is: Why include the upvar types
171 /// in an extra type parameter? The reason for this design is that the
172 /// upvar types can reference lifetimes that are internal to the
173 /// creating function. In my example above, for example, the lifetime
174 /// `'b` represents the scope of the closure itself; this is some
175 /// subset of `foo`, probably just the scope of the call to the to
176 /// `do()`. If we just had the lifetime/type parameters from the
177 /// enclosing function, we couldn't name this lifetime `'b`. Note that
178 /// there can also be lifetimes in the types of the upvars themselves,
179 /// if one of them happens to be a reference to something that the
180 /// creating fn owns.
182 /// OK, you say, so why not create a more minimal set of parameters
183 /// that just includes the extra lifetime parameters? The answer is
184 /// primarily that it would be hard --- we don't know at the time when
185 /// we create the closure type what the full types of the upvars are,
186 /// nor do we know which are borrowed and which are not. In this
187 /// design, we can just supply a fresh type parameter and figure that
190 /// All right, you say, but why include the type parameters from the
191 /// original function then? The answer is that codegen may need them
192 /// when monomorphizing, and they may not appear in the upvars. A
193 /// closure could capture no variables but still make use of some
194 /// in-scope type parameter with a bound (e.g., if our example above
195 /// had an extra `U: Default`, and the closure called `U::default()`).
197 /// There is another reason. This design (implicitly) prohibits
198 /// closures from capturing themselves (except via a trait
199 /// object). This simplifies closure inference considerably, since it
200 /// means that when we infer the kind of a closure or its upvars, we
201 /// don't have to handle cycles where the decisions we make for
202 /// closure C wind up influencing the decisions we ought to make for
203 /// closure C (which would then require fixed point iteration to
204 /// handle). Plus it fixes an ICE. :P
208 /// Generators are handled similarly in `GeneratorSubsts`. The set of
209 /// type parameters is similar, but `CK` and `CS` are replaced by the
210 /// following type parameters:
212 /// * `GS`: The generator's "resume type", which is the type of the
213 /// argument passed to `resume`, and the type of `yield` expressions
214 /// inside the generator.
215 /// * `GY`: The "yield type", which is the type of values passed to
216 /// `yield` inside the generator.
217 /// * `GR`: The "return type", which is the type of value returned upon
218 /// completion of the generator.
219 /// * `GW`: The "generator witness".
220 #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable, Lift)]
221 pub struct ClosureSubsts<'tcx> {
222 /// Lifetime and type parameters from the enclosing function,
223 /// concatenated with a tuple containing the types of the upvars.
225 /// These are separated out because codegen wants to pass them around
226 /// when monomorphizing.
227 pub substs: SubstsRef<'tcx>,
230 /// Struct returned by `split()`.
231 pub struct ClosureSubstsParts<'tcx, T> {
232 pub parent_substs: &'tcx [GenericArg<'tcx>],
233 pub closure_kind_ty: T,
234 pub closure_sig_as_fn_ptr_ty: T,
235 pub tupled_upvars_ty: T,
238 impl<'tcx> ClosureSubsts<'tcx> {
239 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
240 /// for the closure parent, alongside additional closure-specific components.
243 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
244 ) -> ClosureSubsts<'tcx> {
246 substs: tcx.mk_substs(
247 parts.parent_substs.iter().copied().chain(
248 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
250 .map(|&ty| ty.into()),
256 /// Divides the closure substs into their respective components.
257 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
258 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
259 match self.substs[..] {
261 ref parent_substs @ ..,
263 closure_sig_as_fn_ptr_ty,
265 ] => ClosureSubstsParts {
268 closure_sig_as_fn_ptr_ty,
271 _ => bug!("closure substs missing synthetics"),
275 /// Returns `true` only if enough of the synthetic types are known to
276 /// allow using all of the methods on `ClosureSubsts` without panicking.
278 /// Used primarily by `ty::print::pretty` to be able to handle closure
279 /// types that haven't had their synthetic types substituted in.
280 pub fn is_valid(self) -> bool {
281 self.substs.len() >= 3
282 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
285 /// Returns the substitutions of the closure's parent.
286 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
287 self.split().parent_substs
290 /// Returns an iterator over the list of types of captured paths by the closure.
291 /// In case there was a type error in figuring out the types of the captured path, an
292 /// empty iterator is returned.
294 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
295 match self.tupled_upvars_ty().kind() {
296 TyKind::Error(_) => None,
297 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
298 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
299 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
305 /// Returns the tuple type representing the upvars for this closure.
307 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
308 self.split().tupled_upvars_ty.expect_ty()
311 /// Returns the closure kind for this closure; may return a type
312 /// variable during inference. To get the closure kind during
313 /// inference, use `infcx.closure_kind(substs)`.
314 pub fn kind_ty(self) -> Ty<'tcx> {
315 self.split().closure_kind_ty.expect_ty()
318 /// Returns the `fn` pointer type representing the closure signature for this
320 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
321 // type is known at the time of the creation of `ClosureSubsts`,
322 // see `rustc_hir_analysis::check::closure`.
323 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
324 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
327 /// Returns the closure kind for this closure; only usable outside
328 /// of an inference context, because in that context we know that
329 /// there are no type variables.
331 /// If you have an inference context, use `infcx.closure_kind()`.
332 pub fn kind(self) -> ty::ClosureKind {
333 self.kind_ty().to_opt_closure_kind().unwrap()
336 /// Extracts the signature from the closure.
337 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
338 let ty = self.sig_as_fn_ptr_ty();
340 ty::FnPtr(sig) => *sig,
341 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
345 pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
346 ty::print::PrintClosureAsImpl { closure: self }
350 /// Similar to `ClosureSubsts`; see the above documentation for more.
351 #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable, Lift)]
352 pub struct GeneratorSubsts<'tcx> {
353 pub substs: SubstsRef<'tcx>,
356 pub struct GeneratorSubstsParts<'tcx, T> {
357 pub parent_substs: &'tcx [GenericArg<'tcx>],
362 pub tupled_upvars_ty: T,
365 impl<'tcx> GeneratorSubsts<'tcx> {
366 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
367 /// for the generator parent, alongside additional generator-specific components.
370 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
371 ) -> GeneratorSubsts<'tcx> {
373 substs: tcx.mk_substs(
374 parts.parent_substs.iter().copied().chain(
380 parts.tupled_upvars_ty,
383 .map(|&ty| ty.into()),
389 /// Divides the generator substs into their respective components.
390 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
391 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
392 match self.substs[..] {
393 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
394 GeneratorSubstsParts {
403 _ => bug!("generator substs missing synthetics"),
407 /// Returns `true` only if enough of the synthetic types are known to
408 /// allow using all of the methods on `GeneratorSubsts` without panicking.
410 /// Used primarily by `ty::print::pretty` to be able to handle generator
411 /// types that haven't had their synthetic types substituted in.
412 pub fn is_valid(self) -> bool {
413 self.substs.len() >= 5
414 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
417 /// Returns the substitutions of the generator's parent.
418 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
419 self.split().parent_substs
422 /// This describes the types that can be contained in a generator.
423 /// It will be a type variable initially and unified in the last stages of typeck of a body.
424 /// It contains a tuple of all the types that could end up on a generator frame.
425 /// The state transformation MIR pass may only produce layouts which mention types
426 /// in this tuple. Upvars are not counted here.
427 pub fn witness(self) -> Ty<'tcx> {
428 self.split().witness.expect_ty()
431 /// Returns an iterator over the list of types of captured paths by the generator.
432 /// In case there was a type error in figuring out the types of the captured path, an
433 /// empty iterator is returned.
435 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
436 match self.tupled_upvars_ty().kind() {
437 TyKind::Error(_) => None,
438 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
439 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
440 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
446 /// Returns the tuple type representing the upvars for this generator.
448 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
449 self.split().tupled_upvars_ty.expect_ty()
452 /// Returns the type representing the resume type of the generator.
453 pub fn resume_ty(self) -> Ty<'tcx> {
454 self.split().resume_ty.expect_ty()
457 /// Returns the type representing the yield type of the generator.
458 pub fn yield_ty(self) -> Ty<'tcx> {
459 self.split().yield_ty.expect_ty()
462 /// Returns the type representing the return type of the generator.
463 pub fn return_ty(self) -> Ty<'tcx> {
464 self.split().return_ty.expect_ty()
467 /// Returns the "generator signature", which consists of its yield
468 /// and return types.
470 /// N.B., some bits of the code prefers to see this wrapped in a
471 /// binder, but it never contains bound regions. Probably this
472 /// function should be removed.
473 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
474 ty::Binder::dummy(self.sig())
477 /// Returns the "generator signature", which consists of its resume, yield
478 /// and return types.
479 pub fn sig(self) -> GenSig<'tcx> {
481 resume_ty: self.resume_ty(),
482 yield_ty: self.yield_ty(),
483 return_ty: self.return_ty(),
488 impl<'tcx> GeneratorSubsts<'tcx> {
489 /// Generator has not been resumed yet.
490 pub const UNRESUMED: usize = 0;
491 /// Generator has returned or is completed.
492 pub const RETURNED: usize = 1;
493 /// Generator has been poisoned.
494 pub const POISONED: usize = 2;
496 const UNRESUMED_NAME: &'static str = "Unresumed";
497 const RETURNED_NAME: &'static str = "Returned";
498 const POISONED_NAME: &'static str = "Panicked";
500 /// The valid variant indices of this generator.
502 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
503 // FIXME requires optimized MIR
504 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
505 VariantIdx::new(0)..VariantIdx::new(num_variants)
508 /// The discriminant for the given variant. Panics if the `variant_index` is
511 pub fn discriminant_for_variant(
515 variant_index: VariantIdx,
517 // Generators don't support explicit discriminant values, so they are
518 // the same as the variant index.
519 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
520 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
523 /// The set of all discriminants for the generator, enumerated with their
526 pub fn discriminants(
530 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
531 self.variant_range(def_id, tcx).map(move |index| {
532 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
536 /// Calls `f` with a reference to the name of the enumerator for the given
538 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
540 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
541 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
542 Self::POISONED => Cow::from(Self::POISONED_NAME),
543 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
547 /// The type of the state discriminant used in the generator type.
549 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
553 /// This returns the types of the MIR locals which had to be stored across suspension points.
554 /// It is calculated in rustc_mir_transform::generator::StateTransform.
555 /// All the types here must be in the tuple in GeneratorInterior.
557 /// The locals are grouped by their variant number. Note that some locals may
558 /// be repeated in multiple variants.
564 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
565 let layout = tcx.generator_layout(def_id).unwrap();
566 layout.variant_fields.iter().map(move |variant| {
569 .map(move |field| ty::EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
573 /// This is the types of the fields of a generator which are not stored in a
576 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
581 #[derive(Debug, Copy, Clone, HashStable)]
582 pub enum UpvarSubsts<'tcx> {
583 Closure(SubstsRef<'tcx>),
584 Generator(SubstsRef<'tcx>),
587 impl<'tcx> UpvarSubsts<'tcx> {
588 /// Returns an iterator over the list of types of captured paths by the closure/generator.
589 /// In case there was a type error in figuring out the types of the captured path, an
590 /// empty iterator is returned.
592 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
593 let tupled_tys = match self {
594 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
595 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
598 match tupled_tys.kind() {
599 TyKind::Error(_) => None,
600 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
601 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
602 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
609 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
611 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
612 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
617 /// An inline const is modeled like
618 /// ```ignore (illustrative)
619 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
623 /// - 'l0...'li and T0...Tj are the generic parameters
624 /// inherited from the item that defined the inline const,
625 /// - R represents the type of the constant.
627 /// When the inline const is instantiated, `R` is substituted as the actual inferred
628 /// type of the constant. The reason that `R` is represented as an extra type parameter
629 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
630 /// inline const can reference lifetimes that are internal to the creating function.
631 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
632 pub struct InlineConstSubsts<'tcx> {
633 /// Generic parameters from the enclosing item,
634 /// concatenated with the inferred type of the constant.
635 pub substs: SubstsRef<'tcx>,
638 /// Struct returned by `split()`.
639 pub struct InlineConstSubstsParts<'tcx, T> {
640 pub parent_substs: &'tcx [GenericArg<'tcx>],
644 impl<'tcx> InlineConstSubsts<'tcx> {
645 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
648 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
649 ) -> InlineConstSubsts<'tcx> {
651 substs: tcx.mk_substs(
652 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
657 /// Divides the inline const substs into their respective components.
658 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
659 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
660 match self.substs[..] {
661 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
662 _ => bug!("inline const substs missing synthetics"),
666 /// Returns the substitutions of the inline const's parent.
667 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
668 self.split().parent_substs
671 /// Returns the type of this inline const.
672 pub fn ty(self) -> Ty<'tcx> {
673 self.split().ty.expect_ty()
677 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
678 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
679 pub enum ExistentialPredicate<'tcx> {
680 /// E.g., `Iterator`.
681 Trait(ExistentialTraitRef<'tcx>),
682 /// E.g., `Iterator::Item = T`.
683 Projection(ExistentialProjection<'tcx>),
688 impl<'tcx> ExistentialPredicate<'tcx> {
689 /// Compares via an ordering that will not change if modules are reordered or other changes are
690 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
691 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
692 use self::ExistentialPredicate::*;
693 match (*self, *other) {
694 (Trait(_), Trait(_)) => Ordering::Equal,
695 (Projection(ref a), Projection(ref b)) => {
696 tcx.def_path_hash(a.def_id).cmp(&tcx.def_path_hash(b.def_id))
698 (AutoTrait(ref a), AutoTrait(ref b)) => {
699 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
701 (Trait(_), _) => Ordering::Less,
702 (Projection(_), Trait(_)) => Ordering::Greater,
703 (Projection(_), _) => Ordering::Less,
704 (AutoTrait(_), _) => Ordering::Greater,
709 pub type PolyExistentialPredicate<'tcx> = Binder<'tcx, ExistentialPredicate<'tcx>>;
711 impl<'tcx> PolyExistentialPredicate<'tcx> {
712 /// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
713 /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
714 /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
715 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
716 use crate::ty::ToPredicate;
717 match self.skip_binder() {
718 ExistentialPredicate::Trait(tr) => {
719 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
721 ExistentialPredicate::Projection(p) => {
722 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
724 ExistentialPredicate::AutoTrait(did) => {
725 let generics = tcx.generics_of(did);
726 let trait_ref = if generics.params.len() == 1 {
727 tcx.mk_trait_ref(did, [self_ty])
729 // If this is an ill-formed auto trait, then synthesize
730 // new error substs for the missing generics.
732 ty::InternalSubsts::extend_with_error(tcx, did, &[self_ty.into()]);
733 tcx.mk_trait_ref(did, err_substs)
735 self.rebind(trait_ref).without_const().to_predicate(tcx)
741 impl<'tcx> List<ty::PolyExistentialPredicate<'tcx>> {
742 /// Returns the "principal `DefId`" of this set of existential predicates.
744 /// A Rust trait object type consists (in addition to a lifetime bound)
745 /// of a set of trait bounds, which are separated into any number
746 /// of auto-trait bounds, and at most one non-auto-trait bound. The
747 /// non-auto-trait bound is called the "principal" of the trait
750 /// Only the principal can have methods or type parameters (because
751 /// auto traits can have neither of them). This is important, because
752 /// it means the auto traits can be treated as an unordered set (methods
753 /// would force an order for the vtable, while relating traits with
754 /// type parameters without knowing the order to relate them in is
755 /// a rather non-trivial task).
757 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
758 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
759 /// are the set `{Sync}`.
761 /// It is also possible to have a "trivial" trait object that
762 /// consists only of auto traits, with no principal - for example,
763 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
764 /// is `{Send, Sync}`, while there is no principal. These trait objects
765 /// have a "trivial" vtable consisting of just the size, alignment,
767 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
769 .map_bound(|this| match this {
770 ExistentialPredicate::Trait(tr) => Some(tr),
776 pub fn principal_def_id(&self) -> Option<DefId> {
777 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
781 pub fn projection_bounds<'a>(
783 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
784 self.iter().filter_map(|predicate| {
786 .map_bound(|pred| match pred {
787 ExistentialPredicate::Projection(projection) => Some(projection),
795 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'a {
796 self.iter().filter_map(|predicate| match predicate.skip_binder() {
797 ExistentialPredicate::AutoTrait(did) => Some(did),
803 /// A complete reference to a trait. These take numerous guises in syntax,
804 /// but perhaps the most recognizable form is in a where-clause:
805 /// ```ignore (illustrative)
808 /// This would be represented by a trait-reference where the `DefId` is the
809 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
810 /// and `U` as parameter 1.
812 /// Trait references also appear in object types like `Foo<U>`, but in
813 /// that case the `Self` parameter is absent from the substitutions.
814 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
815 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
816 pub struct TraitRef<'tcx> {
818 pub substs: SubstsRef<'tcx>,
819 /// This field exists to prevent the creation of `TraitRef` without
820 /// calling [TyCtxt::mk_trait_ref].
821 pub(super) _use_mk_trait_ref_instead: (),
824 impl<'tcx> TraitRef<'tcx> {
825 pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
828 [self_ty.into()].into_iter().chain(self.substs.iter().skip(1)),
832 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
833 /// are the parameters defined on trait.
834 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
835 ty::Binder::dummy(tcx.mk_trait_ref(def_id, InternalSubsts::identity_for_item(tcx, def_id)))
839 pub fn self_ty(&self) -> Ty<'tcx> {
840 self.substs.type_at(0)
846 substs: SubstsRef<'tcx>,
847 ) -> ty::TraitRef<'tcx> {
848 let defs = tcx.generics_of(trait_id);
849 tcx.mk_trait_ref(trait_id, tcx.intern_substs(&substs[..defs.params.len()]))
853 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
855 impl<'tcx> PolyTraitRef<'tcx> {
856 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
857 self.map_bound_ref(|tr| tr.self_ty())
860 pub fn def_id(&self) -> DefId {
861 self.skip_binder().def_id
865 impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
866 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
867 self.to_string().into_diagnostic_arg()
871 /// An existential reference to a trait, where `Self` is erased.
872 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
873 /// ```ignore (illustrative)
874 /// exists T. T: Trait<'a, 'b, X, Y>
876 /// The substitutions don't include the erased `Self`, only trait
877 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
878 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
879 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
880 pub struct ExistentialTraitRef<'tcx> {
882 pub substs: SubstsRef<'tcx>,
885 impl<'tcx> ExistentialTraitRef<'tcx> {
886 pub fn erase_self_ty(
888 trait_ref: ty::TraitRef<'tcx>,
889 ) -> ty::ExistentialTraitRef<'tcx> {
890 // Assert there is a Self.
891 trait_ref.substs.type_at(0);
893 ty::ExistentialTraitRef {
894 def_id: trait_ref.def_id,
895 substs: tcx.intern_substs(&trait_ref.substs[1..]),
899 /// Object types don't have a self type specified. Therefore, when
900 /// we convert the principal trait-ref into a normal trait-ref,
901 /// you must give *some* self type. A common choice is `mk_err()`
902 /// or some placeholder type.
903 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
904 // otherwise the escaping vars would be captured by the binder
905 // debug_assert!(!self_ty.has_escaping_bound_vars());
907 tcx.mk_trait_ref(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter()))
911 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
913 impl<'tcx> PolyExistentialTraitRef<'tcx> {
914 pub fn def_id(&self) -> DefId {
915 self.skip_binder().def_id
918 /// Object types don't have a self type specified. Therefore, when
919 /// we convert the principal trait-ref into a normal trait-ref,
920 /// you must give *some* self type. A common choice is `mk_err()`
921 /// or some placeholder type.
922 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
923 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
927 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
928 #[derive(HashStable)]
929 pub enum BoundVariableKind {
931 Region(BoundRegionKind),
935 impl BoundVariableKind {
936 pub fn expect_region(self) -> BoundRegionKind {
938 BoundVariableKind::Region(lt) => lt,
939 _ => bug!("expected a region, but found another kind"),
943 pub fn expect_ty(self) -> BoundTyKind {
945 BoundVariableKind::Ty(ty) => ty,
946 _ => bug!("expected a type, but found another kind"),
950 pub fn expect_const(self) {
952 BoundVariableKind::Const => (),
953 _ => bug!("expected a const, but found another kind"),
958 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
959 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
960 /// (which would be represented by the type `PolyTraitRef ==
961 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
962 /// erase, or otherwise "discharge" these bound vars, we change the
963 /// type from `Binder<'tcx, T>` to just `T` (see
964 /// e.g., `liberate_late_bound_regions`).
966 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
967 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
968 #[derive(HashStable, Lift)]
969 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
971 impl<'tcx, T> Binder<'tcx, T>
973 T: TypeVisitable<'tcx>,
975 /// Wraps `value` in a binder, asserting that `value` does not
976 /// contain any bound vars that would be bound by the
977 /// binder. This is commonly used to 'inject' a value T into a
978 /// different binding level.
980 pub fn dummy(value: T) -> Binder<'tcx, T> {
982 !value.has_escaping_bound_vars(),
983 "`{value:?}` has escaping bound vars, so it cannot be wrapped in a dummy binder."
985 Binder(value, ty::List::empty())
988 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
989 if cfg!(debug_assertions) {
990 let mut validator = ValidateBoundVars::new(vars);
991 value.visit_with(&mut validator);
997 impl<'tcx, T> Binder<'tcx, T> {
998 /// Skips the binder and returns the "bound" value. This is a
999 /// risky thing to do because it's easy to get confused about
1000 /// De Bruijn indices and the like. It is usually better to
1001 /// discharge the binder using `no_bound_vars` or
1002 /// `replace_late_bound_regions` or something like
1003 /// that. `skip_binder` is only valid when you are either
1004 /// extracting data that has nothing to do with bound vars, you
1005 /// are doing some sort of test that does not involve bound
1006 /// regions, or you are being very careful about your depth
1009 /// Some examples where `skip_binder` is reasonable:
1011 /// - extracting the `DefId` from a PolyTraitRef;
1012 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1013 /// a type parameter `X`, since the type `X` does not reference any regions
1014 pub fn skip_binder(self) -> T {
1018 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1022 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1023 Binder(&self.0, self.1)
1026 pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
1030 Binder(&self.0, self.1)
1033 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1037 let value = f(&self.0);
1038 Binder(value, self.1)
1041 pub fn map_bound_ref<F, U: TypeVisitable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1045 self.as_ref().map_bound(f)
1048 pub fn map_bound<F, U: TypeVisitable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1052 let value = f(self.0);
1053 if cfg!(debug_assertions) {
1054 let mut validator = ValidateBoundVars::new(self.1);
1055 value.visit_with(&mut validator);
1057 Binder(value, self.1)
1060 pub fn try_map_bound<F, U: TypeVisitable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1062 F: FnOnce(T) -> Result<U, E>,
1064 let value = f(self.0)?;
1065 if cfg!(debug_assertions) {
1066 let mut validator = ValidateBoundVars::new(self.1);
1067 value.visit_with(&mut validator);
1069 Ok(Binder(value, self.1))
1072 /// Wraps a `value` in a binder, using the same bound variables as the
1073 /// current `Binder`. This should not be used if the new value *changes*
1074 /// the bound variables. Note: the (old or new) value itself does not
1075 /// necessarily need to *name* all the bound variables.
1077 /// This currently doesn't do anything different than `bind`, because we
1078 /// don't actually track bound vars. However, semantically, it is different
1079 /// because bound vars aren't allowed to change here, whereas they are
1080 /// in `bind`. This may be (debug) asserted in the future.
1081 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1083 U: TypeVisitable<'tcx>,
1085 if cfg!(debug_assertions) {
1086 let mut validator = ValidateBoundVars::new(self.bound_vars());
1087 value.visit_with(&mut validator);
1089 Binder(value, self.1)
1092 /// Unwraps and returns the value within, but only if it contains
1093 /// no bound vars at all. (In other words, if this binder --
1094 /// and indeed any enclosing binder -- doesn't bind anything at
1095 /// all.) Otherwise, returns `None`.
1097 /// (One could imagine having a method that just unwraps a single
1098 /// binder, but permits late-bound vars bound by enclosing
1099 /// binders, but that would require adjusting the debruijn
1100 /// indices, and given the shallow binding structure we often use,
1101 /// would not be that useful.)
1102 pub fn no_bound_vars(self) -> Option<T>
1104 T: TypeVisitable<'tcx>,
1106 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1109 /// Splits the contents into two things that share the same binder
1110 /// level as the original, returning two distinct binders.
1112 /// `f` should consider bound regions at depth 1 to be free, and
1113 /// anything it produces with bound regions at depth 1 will be
1114 /// bound in the resulting return values.
1115 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1117 F: FnOnce(T) -> (U, V),
1119 let (u, v) = f(self.0);
1120 (Binder(u, self.1), Binder(v, self.1))
1124 impl<'tcx, T> Binder<'tcx, Option<T>> {
1125 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1126 let bound_vars = self.1;
1127 self.0.map(|v| Binder(v, bound_vars))
1131 impl<'tcx, T: IntoIterator> Binder<'tcx, T> {
1132 pub fn iter(self) -> impl Iterator<Item = ty::Binder<'tcx, T::Item>> {
1133 let bound_vars = self.1;
1134 self.0.into_iter().map(|v| Binder(v, bound_vars))
1138 /// Represents the projection of an associated type.
1140 /// For a projection, this would be `<Ty as Trait<...>>::N`.
1142 /// For an opaque type, there is no explicit syntax.
1143 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1144 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1145 pub struct AliasTy<'tcx> {
1146 /// The parameters of the associated or opaque item.
1148 /// For a projection, these are the substitutions for the trait and the
1149 /// GAT substitutions, if there are any.
1151 /// For RPIT the substitutions are for the generics of the function,
1152 /// while for TAIT it is used for the generic parameters of the alias.
1153 pub substs: SubstsRef<'tcx>,
1155 /// The `DefId` of the `TraitItem` for the associated type `N` if this is a projection,
1156 /// or the `OpaqueType` item if this is an opaque.
1158 /// During codegen, `tcx.type_of(def_id)` can be used to get the type of the
1159 /// underlying type if the type is an opaque.
1161 /// Note that if this is an associated type, this is not the `DefId` of the
1162 /// `TraitRef` containing this associated type, which is in `tcx.associated_item(def_id).container`,
1163 /// aka. `tcx.parent(def_id)`.
1166 /// This field exists to prevent the creation of `ProjectionTy` without using
1167 /// [TyCtxt::mk_alias_ty].
1168 pub(super) _use_mk_alias_ty_instead: (),
1171 impl<'tcx> AliasTy<'tcx> {
1172 pub fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId {
1173 match tcx.def_kind(self.def_id) {
1174 DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.def_id),
1175 DefKind::ImplTraitPlaceholder => {
1176 tcx.parent(tcx.impl_trait_in_trait_parent(self.def_id))
1178 kind => bug!("unexpected DefKind in ProjectionTy: {kind:?}"),
1182 /// Extracts the underlying trait reference and own substs from this projection.
1183 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1184 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1185 pub fn trait_ref_and_own_substs(
1188 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1189 debug_assert!(matches!(tcx.def_kind(self.def_id), DefKind::AssocTy | DefKind::AssocConst));
1190 let trait_def_id = self.trait_def_id(tcx);
1191 let trait_generics = tcx.generics_of(trait_def_id);
1193 tcx.mk_trait_ref(trait_def_id, self.substs.truncate_to(tcx, trait_generics)),
1194 &self.substs[trait_generics.count()..],
1198 /// Extracts the underlying trait reference from this projection.
1199 /// For example, if this is a projection of `<T as Iterator>::Item`,
1200 /// then this function would return a `T: Iterator` trait reference.
1202 /// WARNING: This will drop the substs for generic associated types
1203 /// consider calling [Self::trait_ref_and_own_substs] to get those
1205 pub fn trait_ref(self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1206 let def_id = self.trait_def_id(tcx);
1207 tcx.mk_trait_ref(def_id, self.substs.truncate_to(tcx, tcx.generics_of(def_id)))
1210 pub fn self_ty(self) -> Ty<'tcx> {
1211 self.substs.type_at(0)
1214 pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
1215 tcx.mk_alias_ty(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter().skip(1)))
1219 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
1220 pub struct GenSig<'tcx> {
1221 pub resume_ty: Ty<'tcx>,
1222 pub yield_ty: Ty<'tcx>,
1223 pub return_ty: Ty<'tcx>,
1226 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1228 /// Signature of a function type, which we have arbitrarily
1229 /// decided to use to refer to the input/output types.
1231 /// - `inputs`: is the list of arguments and their modes.
1232 /// - `output`: is the return type.
1233 /// - `c_variadic`: indicates whether this is a C-variadic function.
1234 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1235 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1236 pub struct FnSig<'tcx> {
1237 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1238 pub c_variadic: bool,
1239 pub unsafety: hir::Unsafety,
1243 impl<'tcx> FnSig<'tcx> {
1244 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1245 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1248 pub fn output(&self) -> Ty<'tcx> {
1249 self.inputs_and_output[self.inputs_and_output.len() - 1]
1252 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1254 fn fake() -> FnSig<'tcx> {
1256 inputs_and_output: List::empty(),
1258 unsafety: hir::Unsafety::Normal,
1259 abi: abi::Abi::Rust,
1264 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1266 impl<'tcx> PolyFnSig<'tcx> {
1268 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1269 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1272 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1273 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1275 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1276 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1279 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1280 self.map_bound_ref(|fn_sig| fn_sig.output())
1282 pub fn c_variadic(&self) -> bool {
1283 self.skip_binder().c_variadic
1285 pub fn unsafety(&self) -> hir::Unsafety {
1286 self.skip_binder().unsafety
1288 pub fn abi(&self) -> abi::Abi {
1289 self.skip_binder().abi
1293 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1295 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1296 #[derive(HashStable)]
1297 pub struct ParamTy {
1302 impl<'tcx> ParamTy {
1303 pub fn new(index: u32, name: Symbol) -> ParamTy {
1304 ParamTy { index, name }
1307 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1308 ParamTy::new(def.index, def.name)
1312 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1313 tcx.mk_ty_param(self.index, self.name)
1316 pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
1317 let generics = tcx.generics_of(item_with_generics);
1318 let type_param = generics.type_param(self, tcx);
1319 tcx.def_span(type_param.def_id)
1323 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1324 #[derive(HashStable)]
1325 pub struct ParamConst {
1331 pub fn new(index: u32, name: Symbol) -> ParamConst {
1332 ParamConst { index, name }
1335 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1336 ParamConst::new(def.index, def.name)
1340 /// Use this rather than `RegionKind`, whenever possible.
1341 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1342 #[rustc_pass_by_value]
1343 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
1345 impl<'tcx> Deref for Region<'tcx> {
1346 type Target = RegionKind<'tcx>;
1349 fn deref(&self) -> &RegionKind<'tcx> {
1354 impl<'tcx> fmt::Debug for Region<'tcx> {
1355 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1356 write!(f, "{:?}", self.kind())
1360 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1361 #[derive(HashStable)]
1362 pub struct EarlyBoundRegion {
1368 impl fmt::Debug for EarlyBoundRegion {
1369 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1370 write!(f, "{}, {}", self.index, self.name)
1374 /// A **`const`** **v**ariable **ID**.
1375 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1376 #[derive(HashStable, TyEncodable, TyDecodable)]
1377 pub struct ConstVid<'tcx> {
1379 pub phantom: PhantomData<&'tcx ()>,
1382 rustc_index::newtype_index! {
1383 /// A **region** (lifetime) **v**ariable **ID**.
1384 #[derive(HashStable)]
1385 #[debug_format = "'_#{}r"]
1386 pub struct RegionVid {}
1389 impl Atom for RegionVid {
1390 fn index(self) -> usize {
1395 rustc_index::newtype_index! {
1396 #[derive(HashStable)]
1397 pub struct BoundVar {}
1400 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1401 #[derive(HashStable)]
1402 pub struct BoundTy {
1404 pub kind: BoundTyKind,
1407 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1408 #[derive(HashStable)]
1409 pub enum BoundTyKind {
1414 impl From<BoundVar> for BoundTy {
1415 fn from(var: BoundVar) -> Self {
1416 BoundTy { var, kind: BoundTyKind::Anon }
1420 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1421 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1422 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1423 pub struct ExistentialProjection<'tcx> {
1425 pub substs: SubstsRef<'tcx>,
1426 pub term: Term<'tcx>,
1429 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1431 impl<'tcx> ExistentialProjection<'tcx> {
1432 /// Extracts the underlying existential trait reference from this projection.
1433 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1434 /// then this function would return an `exists T. T: Iterator` existential trait
1436 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1437 let def_id = tcx.parent(self.def_id);
1438 let subst_count = tcx.generics_of(def_id).count() - 1;
1439 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1440 ty::ExistentialTraitRef { def_id, substs }
1443 pub fn with_self_ty(
1447 ) -> ty::ProjectionPredicate<'tcx> {
1448 // otherwise the escaping regions would be captured by the binders
1449 debug_assert!(!self_ty.has_escaping_bound_vars());
1451 ty::ProjectionPredicate {
1453 .mk_alias_ty(self.def_id, [self_ty.into()].into_iter().chain(self.substs)),
1458 pub fn erase_self_ty(
1460 projection_predicate: ty::ProjectionPredicate<'tcx>,
1462 // Assert there is a Self.
1463 projection_predicate.projection_ty.substs.type_at(0);
1466 def_id: projection_predicate.projection_ty.def_id,
1467 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1468 term: projection_predicate.term,
1473 impl<'tcx> PolyExistentialProjection<'tcx> {
1474 pub fn with_self_ty(
1478 ) -> ty::PolyProjectionPredicate<'tcx> {
1479 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1482 pub fn item_def_id(&self) -> DefId {
1483 self.skip_binder().def_id
1487 /// Region utilities
1488 impl<'tcx> Region<'tcx> {
1489 pub fn kind(self) -> RegionKind<'tcx> {
1493 pub fn get_name(self) -> Option<Symbol> {
1494 if self.has_name() {
1495 let name = match *self {
1496 ty::ReEarlyBound(ebr) => Some(ebr.name),
1497 ty::ReLateBound(_, br) => br.kind.get_name(),
1498 ty::ReFree(fr) => fr.bound_region.get_name(),
1499 ty::ReStatic => Some(kw::StaticLifetime),
1500 ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
1510 /// Is this region named by the user?
1511 pub fn has_name(self) -> bool {
1513 ty::ReEarlyBound(ebr) => ebr.has_name(),
1514 ty::ReLateBound(_, br) => br.kind.is_named(),
1515 ty::ReFree(fr) => fr.bound_region.is_named(),
1516 ty::ReStatic => true,
1517 ty::ReVar(..) => false,
1518 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1519 ty::ReErased => false,
1524 pub fn is_static(self) -> bool {
1525 matches!(*self, ty::ReStatic)
1529 pub fn is_erased(self) -> bool {
1530 matches!(*self, ty::ReErased)
1534 pub fn is_late_bound(self) -> bool {
1535 matches!(*self, ty::ReLateBound(..))
1539 pub fn is_placeholder(self) -> bool {
1540 matches!(*self, ty::RePlaceholder(..))
1544 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1546 ty::ReLateBound(debruijn, _) => debruijn >= index,
1551 pub fn type_flags(self) -> TypeFlags {
1552 let mut flags = TypeFlags::empty();
1556 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1557 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1558 flags = flags | TypeFlags::HAS_RE_INFER;
1560 ty::RePlaceholder(..) => {
1561 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1562 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1563 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1565 ty::ReEarlyBound(..) => {
1566 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1567 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1568 flags = flags | TypeFlags::HAS_RE_PARAM;
1570 ty::ReFree { .. } => {
1571 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1572 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1575 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1577 ty::ReLateBound(..) => {
1578 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1581 flags = flags | TypeFlags::HAS_RE_ERASED;
1585 debug!("type_flags({:?}) = {:?}", self, flags);
1590 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1591 /// For example, consider the regions in this snippet of code:
1593 /// ```ignore (illustrative)
1595 /// // ^^ -- early bound, declared on an impl
1597 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1598 /// // ^^ ^^ ^ anonymous, late-bound
1599 /// // | early-bound, appears in where-clauses
1600 /// // late-bound, appears only in fn args
1605 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1606 /// of the impl, and for all the other highlighted regions, it
1607 /// would return the `DefId` of the function. In other cases (not shown), this
1608 /// function might return the `DefId` of a closure.
1609 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1611 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1612 ty::ReFree(fr) => fr.scope,
1613 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1617 /// True for free regions other than `'static`.
1618 pub fn is_free(self) -> bool {
1619 matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
1622 /// True if `self` is a free region or static.
1623 pub fn is_free_or_static(self) -> bool {
1625 ty::ReStatic => true,
1626 _ => self.is_free(),
1630 pub fn is_var(self) -> bool {
1631 matches!(self.kind(), ty::ReVar(_))
1636 impl<'tcx> Ty<'tcx> {
1638 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1643 pub fn flags(self) -> TypeFlags {
1648 pub fn is_unit(self) -> bool {
1650 Tuple(ref tys) => tys.is_empty(),
1656 pub fn is_never(self) -> bool {
1657 matches!(self.kind(), Never)
1661 pub fn is_primitive(self) -> bool {
1662 self.kind().is_primitive()
1666 pub fn is_adt(self) -> bool {
1667 matches!(self.kind(), Adt(..))
1671 pub fn is_ref(self) -> bool {
1672 matches!(self.kind(), Ref(..))
1676 pub fn is_ty_var(self) -> bool {
1677 matches!(self.kind(), Infer(TyVar(_)))
1681 pub fn ty_vid(self) -> Option<ty::TyVid> {
1683 &Infer(TyVar(vid)) => Some(vid),
1689 pub fn is_ty_infer(self) -> bool {
1690 matches!(self.kind(), Infer(_))
1694 pub fn is_phantom_data(self) -> bool {
1695 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1699 pub fn is_bool(self) -> bool {
1700 *self.kind() == Bool
1703 /// Returns `true` if this type is a `str`.
1705 pub fn is_str(self) -> bool {
1710 pub fn is_param(self, index: u32) -> bool {
1712 ty::Param(ref data) => data.index == index,
1718 pub fn is_slice(self) -> bool {
1719 matches!(self.kind(), Slice(_))
1723 pub fn is_array_slice(self) -> bool {
1726 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1732 pub fn is_array(self) -> bool {
1733 matches!(self.kind(), Array(..))
1737 pub fn is_simd(self) -> bool {
1739 Adt(def, _) => def.repr().simd(),
1744 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1746 Array(ty, _) | Slice(ty) => *ty,
1747 Str => tcx.types.u8,
1748 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1752 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1754 Adt(def, substs) => {
1755 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1756 let variant = def.non_enum_variant();
1757 let f0_ty = variant.fields[0].ty(tcx, substs);
1759 match f0_ty.kind() {
1760 // If the first field is an array, we assume it is the only field and its
1761 // elements are the SIMD components.
1762 Array(f0_elem_ty, f0_len) => {
1763 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1764 // The way we evaluate the `N` in `[T; N]` here only works since we use
1765 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1766 // if we use it in generic code. See the `simd-array-trait` ui test.
1767 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1769 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1770 // all have the same type).
1771 _ => (variant.fields.len() as u64, f0_ty),
1774 _ => bug!("`simd_size_and_type` called on invalid type"),
1779 pub fn is_region_ptr(self) -> bool {
1780 matches!(self.kind(), Ref(..))
1784 pub fn is_mutable_ptr(self) -> bool {
1787 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1788 | Ref(_, _, hir::Mutability::Mut)
1792 /// Get the mutability of the reference or `None` when not a reference
1794 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1796 Ref(_, _, mutability) => Some(*mutability),
1802 pub fn is_unsafe_ptr(self) -> bool {
1803 matches!(self.kind(), RawPtr(_))
1806 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1808 pub fn is_any_ptr(self) -> bool {
1809 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1813 pub fn is_box(self) -> bool {
1815 Adt(def, _) => def.is_box(),
1820 /// Panics if called on any type other than `Box<T>`.
1821 pub fn boxed_ty(self) -> Ty<'tcx> {
1823 Adt(def, substs) if def.is_box() => substs.type_at(0),
1824 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1828 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1829 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1830 /// contents are abstract to rustc.)
1832 pub fn is_scalar(self) -> bool {
1842 | Infer(IntVar(_) | FloatVar(_))
1846 /// Returns `true` if this type is a floating point type.
1848 pub fn is_floating_point(self) -> bool {
1849 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1853 pub fn is_trait(self) -> bool {
1854 matches!(self.kind(), Dynamic(_, _, ty::Dyn))
1858 pub fn is_dyn_star(self) -> bool {
1859 matches!(self.kind(), Dynamic(_, _, ty::DynStar))
1863 pub fn is_enum(self) -> bool {
1864 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1868 pub fn is_union(self) -> bool {
1869 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1873 pub fn is_closure(self) -> bool {
1874 matches!(self.kind(), Closure(..))
1878 pub fn is_generator(self) -> bool {
1879 matches!(self.kind(), Generator(..))
1883 pub fn is_integral(self) -> bool {
1884 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
1888 pub fn is_fresh_ty(self) -> bool {
1889 matches!(self.kind(), Infer(FreshTy(_)))
1893 pub fn is_fresh(self) -> bool {
1894 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
1898 pub fn is_char(self) -> bool {
1899 matches!(self.kind(), Char)
1903 pub fn is_numeric(self) -> bool {
1904 self.is_integral() || self.is_floating_point()
1908 pub fn is_signed(self) -> bool {
1909 matches!(self.kind(), Int(_))
1913 pub fn is_ptr_sized_integral(self) -> bool {
1914 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
1918 pub fn has_concrete_skeleton(self) -> bool {
1919 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
1922 /// Checks whether a type recursively contains another type
1924 /// Example: `Option<()>` contains `()`
1925 pub fn contains(self, other: Ty<'tcx>) -> bool {
1926 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
1928 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
1931 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1932 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
1936 let cf = self.visit_with(&mut ContainsTyVisitor(other));
1940 /// Returns the type and mutability of `*ty`.
1942 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1943 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1944 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1946 Adt(def, _) if def.is_box() => {
1947 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
1949 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
1950 RawPtr(mt) if explicit => Some(*mt),
1955 /// Returns the type of `ty[i]`.
1956 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
1958 Array(ty, _) | Slice(ty) => Some(*ty),
1963 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
1965 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
1968 // ignore errors (#54954)
1969 ty::Binder::dummy(FnSig::fake())
1971 Closure(..) => bug!(
1972 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1974 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
1979 pub fn is_fn(self) -> bool {
1980 matches!(self.kind(), FnDef(..) | FnPtr(_))
1984 pub fn is_fn_ptr(self) -> bool {
1985 matches!(self.kind(), FnPtr(_))
1989 pub fn is_impl_trait(self) -> bool {
1990 matches!(self.kind(), Alias(ty::Opaque, ..))
1994 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
1996 Adt(adt, _) => Some(*adt),
2001 /// Iterates over tuple fields.
2002 /// Panics when called on anything but a tuple.
2004 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
2006 Tuple(substs) => substs,
2007 _ => bug!("tuple_fields called on non-tuple"),
2011 /// If the type contains variants, returns the valid range of variant indices.
2013 // FIXME: This requires the optimized MIR in the case of generators.
2015 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2017 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2018 TyKind::Generator(def_id, substs, _) => {
2019 Some(substs.as_generator().variant_range(*def_id, tcx))
2025 /// If the type contains variants, returns the variant for `variant_index`.
2026 /// Panics if `variant_index` is out of range.
2028 // FIXME: This requires the optimized MIR in the case of generators.
2030 pub fn discriminant_for_variant(
2033 variant_index: VariantIdx,
2034 ) -> Option<Discr<'tcx>> {
2036 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2037 // This can actually happen during CTFE, see
2038 // https://github.com/rust-lang/rust/issues/89765.
2041 TyKind::Adt(adt, _) if adt.is_enum() => {
2042 Some(adt.discriminant_for_variant(tcx, variant_index))
2044 TyKind::Generator(def_id, substs, _) => {
2045 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2051 /// Returns the type of the discriminant of this type.
2052 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2054 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2055 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2057 ty::Param(_) | ty::Alias(..) | ty::Infer(ty::TyVar(_)) => {
2058 let assoc_items = tcx.associated_item_def_ids(
2059 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2061 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2080 | ty::GeneratorWitness(..)
2084 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2087 | ty::Placeholder(_)
2088 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2089 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2094 /// Returns the type of metadata for (potentially fat) pointers to this type,
2095 /// and a boolean signifying if this is conditional on this type being `Sized`.
2096 pub fn ptr_metadata_ty(
2099 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2100 ) -> (Ty<'tcx>, bool) {
2101 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2104 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2115 | ty::GeneratorWitness(..)
2120 // Extern types have metadata = ().
2122 // If returned by `struct_tail_without_normalization` this is a unit struct
2123 // without any fields, or not a struct, and therefore is Sized.
2125 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2126 // a.k.a. unit type, which is Sized
2127 | ty::Tuple(..) => (tcx.types.unit, false),
2129 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2130 ty::Dynamic(..) => {
2131 let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, None);
2132 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2135 // type parameters only have unit metadata if they're sized, so return true
2136 // to make sure we double check this during confirmation
2137 ty::Param(_) | ty::Alias(..) => (tcx.types.unit, true),
2139 ty::Infer(ty::TyVar(_))
2141 | ty::Placeholder(..)
2142 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2143 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2148 /// When we create a closure, we record its kind (i.e., what trait
2149 /// it implements) into its `ClosureSubsts` using a type
2150 /// parameter. This is kind of a phantom type, except that the
2151 /// most convenient thing for us to are the integral types. This
2152 /// function converts such a special type into the closure
2153 /// kind. To go the other way, use `closure_kind.to_ty(tcx)`.
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_hir_analysis/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::Alias(..) | ty::Param(_) => 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::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
2243 | ty::Float(..) => true,
2245 // The voldemort ZSTs are fine.
2246 ty::FnDef(..) => true,
2248 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2250 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2251 ty::Tuple(field_tys) => {
2252 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2255 // Sometimes traits aren't implemented for every ABI or arity,
2256 // because we can't be generic over everything yet.
2257 ty::FnPtr(..) => false,
2259 // Definitely absolutely not copy.
2260 ty::Ref(_, _, hir::Mutability::Mut) => false,
2262 // Thin pointers & thin shared references are pure-clone-copy, but for
2263 // anything with custom metadata it might be more complicated.
2264 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2266 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2268 // Might be, but not "trivial" so just giving the safe answer.
2269 ty::Adt(..) | ty::Closure(..) => false,
2271 // Needs normalization or revealing to determine, so no is the safe answer.
2272 ty::Alias(..) => false,
2274 ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2276 ty::Bound(..) | ty::Placeholder(..) => {
2277 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2282 /// If `self` is a primitive, return its [`Symbol`].
2283 pub fn primitive_symbol(self) -> Option<Symbol> {
2285 ty::Bool => Some(sym::bool),
2286 ty::Char => Some(sym::char),
2287 ty::Float(f) => match f {
2288 ty::FloatTy::F32 => Some(sym::f32),
2289 ty::FloatTy::F64 => Some(sym::f64),
2291 ty::Int(f) => match f {
2292 ty::IntTy::Isize => Some(sym::isize),
2293 ty::IntTy::I8 => Some(sym::i8),
2294 ty::IntTy::I16 => Some(sym::i16),
2295 ty::IntTy::I32 => Some(sym::i32),
2296 ty::IntTy::I64 => Some(sym::i64),
2297 ty::IntTy::I128 => Some(sym::i128),
2299 ty::Uint(f) => match f {
2300 ty::UintTy::Usize => Some(sym::usize),
2301 ty::UintTy::U8 => Some(sym::u8),
2302 ty::UintTy::U16 => Some(sym::u16),
2303 ty::UintTy::U32 => Some(sym::u32),
2304 ty::UintTy::U64 => Some(sym::u64),
2305 ty::UintTy::U128 => Some(sym::u128),
2312 /// Extra information about why we ended up with a particular variance.
2313 /// This is only used to add more information to error messages, and
2314 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2315 /// may lead to confusing notes in error messages, it will never cause
2316 /// a miscompilation or unsoundness.
2318 /// When in doubt, use `VarianceDiagInfo::default()`
2319 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2320 pub enum VarianceDiagInfo<'tcx> {
2321 /// No additional information - this is the default.
2322 /// We will not add any additional information to error messages.
2325 /// We switched our variance because a generic argument occurs inside
2326 /// the invariant generic argument of another type.
2328 /// The generic type containing the generic parameter
2329 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2331 /// The index of the generic parameter being used
2332 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2337 impl<'tcx> VarianceDiagInfo<'tcx> {
2338 /// Mirrors `Variance::xform` - used to 'combine' the existing
2339 /// and new `VarianceDiagInfo`s when our variance changes.
2340 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2341 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2343 VarianceDiagInfo::None => other,
2344 VarianceDiagInfo::Invariant { .. } => self,