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};
23 use rustc_target::abi::VariantIdx;
24 use rustc_target::spec::abi;
26 use std::cmp::Ordering;
28 use std::marker::PhantomData;
29 use std::ops::{ControlFlow, Deref, Range};
30 use ty::util::IntTypeExt;
32 use rustc_type_ir::sty::TyKind::*;
33 use rustc_type_ir::RegionKind as IrRegionKind;
34 use rustc_type_ir::TyKind as IrTyKind;
36 // Re-export the `TyKind` from `rustc_type_ir` here for convenience
37 #[rustc_diagnostic_item = "TyKind"]
38 pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
39 pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
41 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
42 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
43 pub struct TypeAndMut<'tcx> {
45 pub mutbl: hir::Mutability,
48 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
50 /// A "free" region `fr` can be interpreted as "some region
51 /// at least as big as the scope `fr.scope`".
52 pub struct FreeRegion {
54 pub bound_region: BoundRegionKind,
57 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
59 pub enum BoundRegionKind {
60 /// An anonymous region parameter for a given fn (&T)
63 /// Named region parameters for functions (a in &'a T)
65 /// The `DefId` is needed to distinguish free regions in
66 /// the event of shadowing.
67 BrNamed(DefId, Symbol),
69 /// Anonymous region for the implicit env pointer parameter
74 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
76 pub struct BoundRegion {
78 pub kind: BoundRegionKind,
81 impl BoundRegionKind {
82 pub fn is_named(&self) -> bool {
84 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
89 pub fn get_name(&self) -> Option<Symbol> {
92 BoundRegionKind::BrNamed(_, name) => return Some(name),
102 fn article(&self) -> &'static str;
105 impl<'tcx> Article for TyKind<'tcx> {
106 /// Get the article ("a" or "an") to use with this type.
107 fn article(&self) -> &'static str {
109 Int(_) | Float(_) | Array(_, _) => "an",
110 Adt(def, _) if def.is_enum() => "an",
111 // This should never happen, but ICEing and causing the user's code
112 // to not compile felt too harsh.
119 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
120 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
121 static_assert_size!(TyKind<'_>, 32);
123 /// A closure can be modeled as a struct that looks like:
124 /// ```ignore (illustrative)
125 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
129 /// - 'l0...'li and T0...Tj are the generic parameters
130 /// in scope on the function that defined the closure,
131 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
132 /// is rather hackily encoded via a scalar type. See
133 /// `Ty::to_opt_closure_kind` for details.
134 /// - CS represents the *closure signature*, representing as a `fn()`
135 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
136 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
138 /// - U is a type parameter representing the types of its upvars, tupled up
139 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
140 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
142 /// So, for example, given this function:
143 /// ```ignore (illustrative)
144 /// fn foo<'a, T>(data: &'a mut T) {
145 /// do(|| data.count += 1)
148 /// the type of the closure would be something like:
149 /// ```ignore (illustrative)
150 /// struct Closure<'a, T, U>(...U);
152 /// Note that the type of the upvar is not specified in the struct.
153 /// You may wonder how the impl would then be able to use the upvar,
154 /// if it doesn't know it's type? The answer is that the impl is
155 /// (conceptually) not fully generic over Closure but rather tied to
156 /// instances with the expected upvar types:
157 /// ```ignore (illustrative)
158 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
162 /// You can see that the *impl* fully specified the type of the upvar
163 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
164 /// (Here, I am assuming that `data` is mut-borrowed.)
166 /// Now, the last question you may ask is: Why include the upvar types
167 /// in an extra type parameter? The reason for this design is that the
168 /// upvar types can reference lifetimes that are internal to the
169 /// creating function. In my example above, for example, the lifetime
170 /// `'b` represents the scope of the closure itself; this is some
171 /// subset of `foo`, probably just the scope of the call to the to
172 /// `do()`. If we just had the lifetime/type parameters from the
173 /// enclosing function, we couldn't name this lifetime `'b`. Note that
174 /// there can also be lifetimes in the types of the upvars themselves,
175 /// if one of them happens to be a reference to something that the
176 /// creating fn owns.
178 /// OK, you say, so why not create a more minimal set of parameters
179 /// that just includes the extra lifetime parameters? The answer is
180 /// primarily that it would be hard --- we don't know at the time when
181 /// we create the closure type what the full types of the upvars are,
182 /// nor do we know which are borrowed and which are not. In this
183 /// design, we can just supply a fresh type parameter and figure that
186 /// All right, you say, but why include the type parameters from the
187 /// original function then? The answer is that codegen may need them
188 /// when monomorphizing, and they may not appear in the upvars. A
189 /// closure could capture no variables but still make use of some
190 /// in-scope type parameter with a bound (e.g., if our example above
191 /// had an extra `U: Default`, and the closure called `U::default()`).
193 /// There is another reason. This design (implicitly) prohibits
194 /// closures from capturing themselves (except via a trait
195 /// object). This simplifies closure inference considerably, since it
196 /// means that when we infer the kind of a closure or its upvars, we
197 /// don't have to handle cycles where the decisions we make for
198 /// closure C wind up influencing the decisions we ought to make for
199 /// closure C (which would then require fixed point iteration to
200 /// handle). Plus it fixes an ICE. :P
204 /// Generators are handled similarly in `GeneratorSubsts`. The set of
205 /// type parameters is similar, but `CK` and `CS` are replaced by the
206 /// following type parameters:
208 /// * `GS`: The generator's "resume type", which is the type of the
209 /// argument passed to `resume`, and the type of `yield` expressions
210 /// inside the generator.
211 /// * `GY`: The "yield type", which is the type of values passed to
212 /// `yield` inside the generator.
213 /// * `GR`: The "return type", which is the type of value returned upon
214 /// completion of the generator.
215 /// * `GW`: The "generator witness".
216 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
217 pub struct ClosureSubsts<'tcx> {
218 /// Lifetime and type parameters from the enclosing function,
219 /// concatenated with a tuple containing the types of the upvars.
221 /// These are separated out because codegen wants to pass them around
222 /// when monomorphizing.
223 pub substs: SubstsRef<'tcx>,
226 /// Struct returned by `split()`.
227 pub struct ClosureSubstsParts<'tcx, T> {
228 pub parent_substs: &'tcx [GenericArg<'tcx>],
229 pub closure_kind_ty: T,
230 pub closure_sig_as_fn_ptr_ty: T,
231 pub tupled_upvars_ty: T,
234 impl<'tcx> ClosureSubsts<'tcx> {
235 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
236 /// for the closure parent, alongside additional closure-specific components.
239 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
240 ) -> ClosureSubsts<'tcx> {
242 substs: tcx.mk_substs(
243 parts.parent_substs.iter().copied().chain(
244 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
246 .map(|&ty| ty.into()),
252 /// Divides the closure substs into their respective components.
253 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
254 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
255 match self.substs[..] {
257 ref parent_substs @ ..,
259 closure_sig_as_fn_ptr_ty,
261 ] => ClosureSubstsParts {
264 closure_sig_as_fn_ptr_ty,
267 _ => bug!("closure substs missing synthetics"),
271 /// Returns `true` only if enough of the synthetic types are known to
272 /// allow using all of the methods on `ClosureSubsts` without panicking.
274 /// Used primarily by `ty::print::pretty` to be able to handle closure
275 /// types that haven't had their synthetic types substituted in.
276 pub fn is_valid(self) -> bool {
277 self.substs.len() >= 3
278 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
281 /// Returns the substitutions of the closure's parent.
282 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
283 self.split().parent_substs
286 /// Returns an iterator over the list of types of captured paths by the closure.
287 /// In case there was a type error in figuring out the types of the captured path, an
288 /// empty iterator is returned.
290 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
291 match self.tupled_upvars_ty().kind() {
292 TyKind::Error(_) => None,
293 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
294 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
295 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
301 /// Returns the tuple type representing the upvars for this closure.
303 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
304 self.split().tupled_upvars_ty.expect_ty()
307 /// Returns the closure kind for this closure; may return a type
308 /// variable during inference. To get the closure kind during
309 /// inference, use `infcx.closure_kind(substs)`.
310 pub fn kind_ty(self) -> Ty<'tcx> {
311 self.split().closure_kind_ty.expect_ty()
314 /// Returns the `fn` pointer type representing the closure signature for this
316 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
317 // type is known at the time of the creation of `ClosureSubsts`,
318 // see `rustc_hir_analysis::check::closure`.
319 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
320 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
323 /// Returns the closure kind for this closure; only usable outside
324 /// of an inference context, because in that context we know that
325 /// there are no type variables.
327 /// If you have an inference context, use `infcx.closure_kind()`.
328 pub fn kind(self) -> ty::ClosureKind {
329 self.kind_ty().to_opt_closure_kind().unwrap()
332 /// Extracts the signature from the closure.
333 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
334 let ty = self.sig_as_fn_ptr_ty();
336 ty::FnPtr(sig) => *sig,
337 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
341 pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
342 ty::print::PrintClosureAsImpl { closure: self }
346 /// Similar to `ClosureSubsts`; see the above documentation for more.
347 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
348 pub struct GeneratorSubsts<'tcx> {
349 pub substs: SubstsRef<'tcx>,
352 pub struct GeneratorSubstsParts<'tcx, T> {
353 pub parent_substs: &'tcx [GenericArg<'tcx>],
358 pub tupled_upvars_ty: T,
361 impl<'tcx> GeneratorSubsts<'tcx> {
362 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
363 /// for the generator parent, alongside additional generator-specific components.
366 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
367 ) -> GeneratorSubsts<'tcx> {
369 substs: tcx.mk_substs(
370 parts.parent_substs.iter().copied().chain(
376 parts.tupled_upvars_ty,
379 .map(|&ty| ty.into()),
385 /// Divides the generator substs into their respective components.
386 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
387 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
388 match self.substs[..] {
389 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
390 GeneratorSubstsParts {
399 _ => bug!("generator substs missing synthetics"),
403 /// Returns `true` only if enough of the synthetic types are known to
404 /// allow using all of the methods on `GeneratorSubsts` without panicking.
406 /// Used primarily by `ty::print::pretty` to be able to handle generator
407 /// types that haven't had their synthetic types substituted in.
408 pub fn is_valid(self) -> bool {
409 self.substs.len() >= 5
410 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
413 /// Returns the substitutions of the generator's parent.
414 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
415 self.split().parent_substs
418 /// This describes the types that can be contained in a generator.
419 /// It will be a type variable initially and unified in the last stages of typeck of a body.
420 /// It contains a tuple of all the types that could end up on a generator frame.
421 /// The state transformation MIR pass may only produce layouts which mention types
422 /// in this tuple. Upvars are not counted here.
423 pub fn witness(self) -> Ty<'tcx> {
424 self.split().witness.expect_ty()
427 /// Returns an iterator over the list of types of captured paths by the generator.
428 /// In case there was a type error in figuring out the types of the captured path, an
429 /// empty iterator is returned.
431 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
432 match self.tupled_upvars_ty().kind() {
433 TyKind::Error(_) => None,
434 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
435 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
436 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
442 /// Returns the tuple type representing the upvars for this generator.
444 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
445 self.split().tupled_upvars_ty.expect_ty()
448 /// Returns the type representing the resume type of the generator.
449 pub fn resume_ty(self) -> Ty<'tcx> {
450 self.split().resume_ty.expect_ty()
453 /// Returns the type representing the yield type of the generator.
454 pub fn yield_ty(self) -> Ty<'tcx> {
455 self.split().yield_ty.expect_ty()
458 /// Returns the type representing the return type of the generator.
459 pub fn return_ty(self) -> Ty<'tcx> {
460 self.split().return_ty.expect_ty()
463 /// Returns the "generator signature", which consists of its yield
464 /// and return types.
466 /// N.B., some bits of the code prefers to see this wrapped in a
467 /// binder, but it never contains bound regions. Probably this
468 /// function should be removed.
469 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
470 ty::Binder::dummy(self.sig())
473 /// Returns the "generator signature", which consists of its resume, yield
474 /// and return types.
475 pub fn sig(self) -> GenSig<'tcx> {
477 resume_ty: self.resume_ty(),
478 yield_ty: self.yield_ty(),
479 return_ty: self.return_ty(),
484 impl<'tcx> GeneratorSubsts<'tcx> {
485 /// Generator has not been resumed yet.
486 pub const UNRESUMED: usize = 0;
487 /// Generator has returned or is completed.
488 pub const RETURNED: usize = 1;
489 /// Generator has been poisoned.
490 pub const POISONED: usize = 2;
492 const UNRESUMED_NAME: &'static str = "Unresumed";
493 const RETURNED_NAME: &'static str = "Returned";
494 const POISONED_NAME: &'static str = "Panicked";
496 /// The valid variant indices of this generator.
498 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
499 // FIXME requires optimized MIR
500 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
501 VariantIdx::new(0)..VariantIdx::new(num_variants)
504 /// The discriminant for the given variant. Panics if the `variant_index` is
507 pub fn discriminant_for_variant(
511 variant_index: VariantIdx,
513 // Generators don't support explicit discriminant values, so they are
514 // the same as the variant index.
515 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
516 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
519 /// The set of all discriminants for the generator, enumerated with their
522 pub fn discriminants(
526 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
527 self.variant_range(def_id, tcx).map(move |index| {
528 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
532 /// Calls `f` with a reference to the name of the enumerator for the given
534 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
536 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
537 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
538 Self::POISONED => Cow::from(Self::POISONED_NAME),
539 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
543 /// The type of the state discriminant used in the generator type.
545 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
549 /// This returns the types of the MIR locals which had to be stored across suspension points.
550 /// It is calculated in rustc_mir_transform::generator::StateTransform.
551 /// All the types here must be in the tuple in GeneratorInterior.
553 /// The locals are grouped by their variant number. Note that some locals may
554 /// be repeated in multiple variants.
560 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
561 let layout = tcx.generator_layout(def_id).unwrap();
562 layout.variant_fields.iter().map(move |variant| {
565 .map(move |field| ty::EarlyBinder(layout.field_tys[*field]).subst(tcx, self.substs))
569 /// This is the types of the fields of a generator which are not stored in a
572 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
577 #[derive(Debug, Copy, Clone, HashStable)]
578 pub enum UpvarSubsts<'tcx> {
579 Closure(SubstsRef<'tcx>),
580 Generator(SubstsRef<'tcx>),
583 impl<'tcx> UpvarSubsts<'tcx> {
584 /// Returns an iterator over the list of types of captured paths by the closure/generator.
585 /// In case there was a type error in figuring out the types of the captured path, an
586 /// empty iterator is returned.
588 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
589 let tupled_tys = match self {
590 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
591 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
594 match tupled_tys.kind() {
595 TyKind::Error(_) => None,
596 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
597 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
598 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
605 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
607 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
608 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
613 /// An inline const is modeled like
614 /// ```ignore (illustrative)
615 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
619 /// - 'l0...'li and T0...Tj are the generic parameters
620 /// inherited from the item that defined the inline const,
621 /// - R represents the type of the constant.
623 /// When the inline const is instantiated, `R` is substituted as the actual inferred
624 /// type of the constant. The reason that `R` is represented as an extra type parameter
625 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
626 /// inline const can reference lifetimes that are internal to the creating function.
627 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
628 pub struct InlineConstSubsts<'tcx> {
629 /// Generic parameters from the enclosing item,
630 /// concatenated with the inferred type of the constant.
631 pub substs: SubstsRef<'tcx>,
634 /// Struct returned by `split()`.
635 pub struct InlineConstSubstsParts<'tcx, T> {
636 pub parent_substs: &'tcx [GenericArg<'tcx>],
640 impl<'tcx> InlineConstSubsts<'tcx> {
641 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
644 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
645 ) -> InlineConstSubsts<'tcx> {
647 substs: tcx.mk_substs(
648 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
653 /// Divides the inline const substs into their respective components.
654 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
655 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
656 match self.substs[..] {
657 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
658 _ => bug!("inline const substs missing synthetics"),
662 /// Returns the substitutions of the inline const's parent.
663 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
664 self.split().parent_substs
667 /// Returns the type of this inline const.
668 pub fn ty(self) -> Ty<'tcx> {
669 self.split().ty.expect_ty()
673 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
674 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
675 pub enum ExistentialPredicate<'tcx> {
676 /// E.g., `Iterator`.
677 Trait(ExistentialTraitRef<'tcx>),
678 /// E.g., `Iterator::Item = T`.
679 Projection(ExistentialProjection<'tcx>),
684 impl<'tcx> ExistentialPredicate<'tcx> {
685 /// Compares via an ordering that will not change if modules are reordered or other changes are
686 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
687 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
688 use self::ExistentialPredicate::*;
689 match (*self, *other) {
690 (Trait(_), Trait(_)) => Ordering::Equal,
691 (Projection(ref a), Projection(ref b)) => {
692 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
694 (AutoTrait(ref a), AutoTrait(ref b)) => {
695 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
697 (Trait(_), _) => Ordering::Less,
698 (Projection(_), Trait(_)) => Ordering::Greater,
699 (Projection(_), _) => Ordering::Less,
700 (AutoTrait(_), _) => Ordering::Greater,
705 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
706 /// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
707 /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
708 /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
709 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
710 use crate::ty::ToPredicate;
711 match self.skip_binder() {
712 ExistentialPredicate::Trait(tr) => {
713 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
715 ExistentialPredicate::Projection(p) => {
716 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
718 ExistentialPredicate::AutoTrait(did) => {
719 let trait_ref = self.rebind(ty::TraitRef {
721 substs: tcx.mk_substs_trait(self_ty, &[]),
723 trait_ref.without_const().to_predicate(tcx)
729 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
730 /// Returns the "principal `DefId`" of this set of existential predicates.
732 /// A Rust trait object type consists (in addition to a lifetime bound)
733 /// of a set of trait bounds, which are separated into any number
734 /// of auto-trait bounds, and at most one non-auto-trait bound. The
735 /// non-auto-trait bound is called the "principal" of the trait
738 /// Only the principal can have methods or type parameters (because
739 /// auto traits can have neither of them). This is important, because
740 /// it means the auto traits can be treated as an unordered set (methods
741 /// would force an order for the vtable, while relating traits with
742 /// type parameters without knowing the order to relate them in is
743 /// a rather non-trivial task).
745 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
746 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
747 /// are the set `{Sync}`.
749 /// It is also possible to have a "trivial" trait object that
750 /// consists only of auto traits, with no principal - for example,
751 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
752 /// is `{Send, Sync}`, while there is no principal. These trait objects
753 /// have a "trivial" vtable consisting of just the size, alignment,
755 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
757 .map_bound(|this| match this {
758 ExistentialPredicate::Trait(tr) => Some(tr),
764 pub fn principal_def_id(&self) -> Option<DefId> {
765 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
769 pub fn projection_bounds<'a>(
771 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
772 self.iter().filter_map(|predicate| {
774 .map_bound(|pred| match pred {
775 ExistentialPredicate::Projection(projection) => Some(projection),
783 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'a {
784 self.iter().filter_map(|predicate| match predicate.skip_binder() {
785 ExistentialPredicate::AutoTrait(did) => Some(did),
791 /// A complete reference to a trait. These take numerous guises in syntax,
792 /// but perhaps the most recognizable form is in a where-clause:
793 /// ```ignore (illustrative)
796 /// This would be represented by a trait-reference where the `DefId` is the
797 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
798 /// and `U` as parameter 1.
800 /// Trait references also appear in object types like `Foo<U>`, but in
801 /// that case the `Self` parameter is absent from the substitutions.
802 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
803 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
804 pub struct TraitRef<'tcx> {
806 pub substs: SubstsRef<'tcx>,
809 impl<'tcx> TraitRef<'tcx> {
810 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
811 TraitRef { def_id, substs }
814 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
815 /// are the parameters defined on trait.
816 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
817 ty::Binder::dummy(TraitRef {
819 substs: InternalSubsts::identity_for_item(tcx, def_id),
824 pub fn self_ty(&self) -> Ty<'tcx> {
825 self.substs.type_at(0)
831 substs: SubstsRef<'tcx>,
832 ) -> ty::TraitRef<'tcx> {
833 let defs = tcx.generics_of(trait_id);
834 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
838 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
840 impl<'tcx> PolyTraitRef<'tcx> {
841 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
842 self.map_bound_ref(|tr| tr.self_ty())
845 pub fn def_id(&self) -> DefId {
846 self.skip_binder().def_id
849 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
850 self.map_bound(|trait_ref| ty::TraitPredicate {
852 constness: ty::BoundConstness::NotConst,
853 polarity: ty::ImplPolarity::Positive,
857 /// Same as [`PolyTraitRef::to_poly_trait_predicate`] but sets a negative polarity instead.
858 pub fn to_poly_trait_predicate_negative_polarity(&self) -> ty::PolyTraitPredicate<'tcx> {
859 self.map_bound(|trait_ref| ty::TraitPredicate {
861 constness: ty::BoundConstness::NotConst,
862 polarity: ty::ImplPolarity::Negative,
867 impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> {
868 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
869 self.to_string().into_diagnostic_arg()
873 /// An existential reference to a trait, where `Self` is erased.
874 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
875 /// ```ignore (illustrative)
876 /// exists T. T: Trait<'a, 'b, X, Y>
878 /// The substitutions don't include the erased `Self`, only trait
879 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
880 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
881 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
882 pub struct ExistentialTraitRef<'tcx> {
884 pub substs: SubstsRef<'tcx>,
887 impl<'tcx> ExistentialTraitRef<'tcx> {
888 pub fn erase_self_ty(
890 trait_ref: ty::TraitRef<'tcx>,
891 ) -> ty::ExistentialTraitRef<'tcx> {
892 // Assert there is a Self.
893 trait_ref.substs.type_at(0);
895 ty::ExistentialTraitRef {
896 def_id: trait_ref.def_id,
897 substs: tcx.intern_substs(&trait_ref.substs[1..]),
901 /// Object types don't have a self type specified. Therefore, when
902 /// we convert the principal trait-ref into a normal trait-ref,
903 /// you must give *some* self type. A common choice is `mk_err()`
904 /// or some placeholder type.
905 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
906 // otherwise the escaping vars would be captured by the binder
907 // debug_assert!(!self_ty.has_escaping_bound_vars());
909 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
913 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
915 impl<'tcx> PolyExistentialTraitRef<'tcx> {
916 pub fn def_id(&self) -> DefId {
917 self.skip_binder().def_id
920 /// Object types don't have a self type specified. Therefore, when
921 /// we convert the principal trait-ref into a normal trait-ref,
922 /// you must give *some* self type. A common choice is `mk_err()`
923 /// or some placeholder type.
924 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
925 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
929 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
930 #[derive(HashStable)]
931 pub enum BoundVariableKind {
933 Region(BoundRegionKind),
937 impl BoundVariableKind {
938 pub fn expect_region(self) -> BoundRegionKind {
940 BoundVariableKind::Region(lt) => lt,
941 _ => bug!("expected a region, but found another kind"),
945 pub fn expect_ty(self) -> BoundTyKind {
947 BoundVariableKind::Ty(ty) => ty,
948 _ => bug!("expected a type, but found another kind"),
952 pub fn expect_const(self) {
954 BoundVariableKind::Const => (),
955 _ => bug!("expected a const, but found another kind"),
960 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
961 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
962 /// (which would be represented by the type `PolyTraitRef ==
963 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
964 /// erase, or otherwise "discharge" these bound vars, we change the
965 /// type from `Binder<'tcx, T>` to just `T` (see
966 /// e.g., `liberate_late_bound_regions`).
968 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
969 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
970 #[derive(HashStable, Lift)]
971 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
973 impl<'tcx, T> Binder<'tcx, T>
975 T: TypeVisitable<'tcx>,
977 /// Wraps `value` in a binder, asserting that `value` does not
978 /// contain any bound vars that would be bound by the
979 /// binder. This is commonly used to 'inject' a value T into a
980 /// different binding level.
981 pub fn dummy(value: T) -> Binder<'tcx, T> {
982 assert!(!value.has_escaping_bound_vars());
983 Binder(value, ty::List::empty())
986 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
987 if cfg!(debug_assertions) {
988 let mut validator = ValidateBoundVars::new(vars);
989 value.visit_with(&mut validator);
995 impl<'tcx, T> Binder<'tcx, T> {
996 /// Skips the binder and returns the "bound" value. This is a
997 /// risky thing to do because it's easy to get confused about
998 /// De Bruijn indices and the like. It is usually better to
999 /// discharge the binder using `no_bound_vars` or
1000 /// `replace_late_bound_regions` or something like
1001 /// that. `skip_binder` is only valid when you are either
1002 /// extracting data that has nothing to do with bound vars, you
1003 /// are doing some sort of test that does not involve bound
1004 /// regions, or you are being very careful about your depth
1007 /// Some examples where `skip_binder` is reasonable:
1009 /// - extracting the `DefId` from a PolyTraitRef;
1010 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1011 /// a type parameter `X`, since the type `X` does not reference any regions
1012 pub fn skip_binder(self) -> T {
1016 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1020 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1021 Binder(&self.0, self.1)
1024 pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
1028 Binder(&self.0, self.1)
1031 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1035 let value = f(&self.0);
1036 Binder(value, self.1)
1039 pub fn map_bound_ref<F, U: TypeVisitable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1043 self.as_ref().map_bound(f)
1046 pub fn map_bound<F, U: TypeVisitable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1050 let value = f(self.0);
1051 if cfg!(debug_assertions) {
1052 let mut validator = ValidateBoundVars::new(self.1);
1053 value.visit_with(&mut validator);
1055 Binder(value, self.1)
1058 pub fn try_map_bound<F, U: TypeVisitable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1060 F: FnOnce(T) -> Result<U, E>,
1062 let value = f(self.0)?;
1063 if cfg!(debug_assertions) {
1064 let mut validator = ValidateBoundVars::new(self.1);
1065 value.visit_with(&mut validator);
1067 Ok(Binder(value, self.1))
1070 /// Wraps a `value` in a binder, using the same bound variables as the
1071 /// current `Binder`. This should not be used if the new value *changes*
1072 /// the bound variables. Note: the (old or new) value itself does not
1073 /// necessarily need to *name* all the bound variables.
1075 /// This currently doesn't do anything different than `bind`, because we
1076 /// don't actually track bound vars. However, semantically, it is different
1077 /// because bound vars aren't allowed to change here, whereas they are
1078 /// in `bind`. This may be (debug) asserted in the future.
1079 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1081 U: TypeVisitable<'tcx>,
1083 if cfg!(debug_assertions) {
1084 let mut validator = ValidateBoundVars::new(self.bound_vars());
1085 value.visit_with(&mut validator);
1087 Binder(value, self.1)
1090 /// Unwraps and returns the value within, but only if it contains
1091 /// no bound vars at all. (In other words, if this binder --
1092 /// and indeed any enclosing binder -- doesn't bind anything at
1093 /// all.) Otherwise, returns `None`.
1095 /// (One could imagine having a method that just unwraps a single
1096 /// binder, but permits late-bound vars bound by enclosing
1097 /// binders, but that would require adjusting the debruijn
1098 /// indices, and given the shallow binding structure we often use,
1099 /// would not be that useful.)
1100 pub fn no_bound_vars(self) -> Option<T>
1102 T: TypeVisitable<'tcx>,
1104 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1107 /// Splits the contents into two things that share the same binder
1108 /// level as the original, returning two distinct binders.
1110 /// `f` should consider bound regions at depth 1 to be free, and
1111 /// anything it produces with bound regions at depth 1 will be
1112 /// bound in the resulting return values.
1113 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1115 F: FnOnce(T) -> (U, V),
1117 let (u, v) = f(self.0);
1118 (Binder(u, self.1), Binder(v, self.1))
1122 impl<'tcx, T> Binder<'tcx, Option<T>> {
1123 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1124 let bound_vars = self.1;
1125 self.0.map(|v| Binder(v, bound_vars))
1129 /// Represents the projection of an associated type. In explicit UFCS
1130 /// form this would be written `<T as Trait<..>>::N`.
1131 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1132 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1133 pub struct ProjectionTy<'tcx> {
1134 /// The parameters of the associated item.
1135 pub substs: SubstsRef<'tcx>,
1137 /// The `DefId` of the `TraitItem` for the associated type `N`.
1139 /// Note that this is not the `DefId` of the `TraitRef` containing this
1140 /// associated type, which is in `tcx.associated_item(item_def_id).container`,
1141 /// aka. `tcx.parent(item_def_id).unwrap()`.
1142 pub item_def_id: DefId,
1145 impl<'tcx> ProjectionTy<'tcx> {
1146 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1147 match tcx.def_kind(self.item_def_id) {
1148 DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.item_def_id),
1149 DefKind::ImplTraitPlaceholder => {
1150 tcx.parent(tcx.impl_trait_in_trait_parent(self.item_def_id))
1152 kind => bug!("unexpected DefKind in ProjectionTy: {kind:?}"),
1156 /// Extracts the underlying trait reference and own substs from this projection.
1157 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1158 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1159 pub fn trait_ref_and_own_substs(
1162 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1163 let def_id = tcx.parent(self.item_def_id);
1164 let trait_generics = tcx.generics_of(def_id);
1166 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1167 &self.substs[trait_generics.count()..],
1171 /// Extracts the underlying trait reference from this projection.
1172 /// For example, if this is a projection of `<T as Iterator>::Item`,
1173 /// then this function would return a `T: Iterator` trait reference.
1175 /// WARNING: This will drop the substs for generic associated types
1176 /// consider calling [Self::trait_ref_and_own_substs] to get those
1178 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1179 let def_id = self.trait_def_id(tcx);
1180 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1183 pub fn self_ty(&self) -> Ty<'tcx> {
1184 self.substs.type_at(0)
1188 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
1189 pub struct GenSig<'tcx> {
1190 pub resume_ty: Ty<'tcx>,
1191 pub yield_ty: Ty<'tcx>,
1192 pub return_ty: Ty<'tcx>,
1195 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1197 /// Signature of a function type, which we have arbitrarily
1198 /// decided to use to refer to the input/output types.
1200 /// - `inputs`: is the list of arguments and their modes.
1201 /// - `output`: is the return type.
1202 /// - `c_variadic`: indicates whether this is a C-variadic function.
1203 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1204 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1205 pub struct FnSig<'tcx> {
1206 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1207 pub c_variadic: bool,
1208 pub unsafety: hir::Unsafety,
1212 impl<'tcx> FnSig<'tcx> {
1213 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1214 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1217 pub fn output(&self) -> Ty<'tcx> {
1218 self.inputs_and_output[self.inputs_and_output.len() - 1]
1221 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1223 fn fake() -> FnSig<'tcx> {
1225 inputs_and_output: List::empty(),
1227 unsafety: hir::Unsafety::Normal,
1228 abi: abi::Abi::Rust,
1233 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1235 impl<'tcx> PolyFnSig<'tcx> {
1237 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1238 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1241 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1242 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1244 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1245 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1248 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1249 self.map_bound_ref(|fn_sig| fn_sig.output())
1251 pub fn c_variadic(&self) -> bool {
1252 self.skip_binder().c_variadic
1254 pub fn unsafety(&self) -> hir::Unsafety {
1255 self.skip_binder().unsafety
1257 pub fn abi(&self) -> abi::Abi {
1258 self.skip_binder().abi
1262 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1264 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1265 #[derive(HashStable)]
1266 pub struct ParamTy {
1271 impl<'tcx> ParamTy {
1272 pub fn new(index: u32, name: Symbol) -> ParamTy {
1273 ParamTy { index, name }
1276 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1277 ParamTy::new(def.index, def.name)
1281 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1282 tcx.mk_ty_param(self.index, self.name)
1286 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1287 #[derive(HashStable)]
1288 pub struct ParamConst {
1294 pub fn new(index: u32, name: Symbol) -> ParamConst {
1295 ParamConst { index, name }
1298 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1299 ParamConst::new(def.index, def.name)
1303 /// Use this rather than `RegionKind`, whenever possible.
1304 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
1305 #[rustc_pass_by_value]
1306 pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
1308 impl<'tcx> Deref for Region<'tcx> {
1309 type Target = RegionKind<'tcx>;
1312 fn deref(&self) -> &RegionKind<'tcx> {
1317 impl<'tcx> fmt::Debug for Region<'tcx> {
1318 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1319 write!(f, "{:?}", self.kind())
1323 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1324 #[derive(HashStable)]
1325 pub struct EarlyBoundRegion {
1331 impl fmt::Debug for EarlyBoundRegion {
1332 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1333 write!(f, "{}, {}", self.index, self.name)
1337 /// A **`const`** **v**ariable **ID**.
1338 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1339 #[derive(HashStable, TyEncodable, TyDecodable)]
1340 pub struct ConstVid<'tcx> {
1342 pub phantom: PhantomData<&'tcx ()>,
1345 rustc_index::newtype_index! {
1346 /// A **region** (lifetime) **v**ariable **ID**.
1347 #[derive(HashStable)]
1348 pub struct RegionVid {
1349 DEBUG_FORMAT = custom,
1353 impl Atom for RegionVid {
1354 fn index(self) -> usize {
1359 rustc_index::newtype_index! {
1360 #[derive(HashStable)]
1361 pub struct BoundVar { .. }
1364 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1365 #[derive(HashStable)]
1366 pub struct BoundTy {
1368 pub kind: BoundTyKind,
1371 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1372 #[derive(HashStable)]
1373 pub enum BoundTyKind {
1378 impl From<BoundVar> for BoundTy {
1379 fn from(var: BoundVar) -> Self {
1380 BoundTy { var, kind: BoundTyKind::Anon }
1384 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1385 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1386 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1387 pub struct ExistentialProjection<'tcx> {
1388 pub item_def_id: DefId,
1389 pub substs: SubstsRef<'tcx>,
1390 pub term: Term<'tcx>,
1393 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1395 impl<'tcx> ExistentialProjection<'tcx> {
1396 /// Extracts the underlying existential trait reference from this projection.
1397 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1398 /// then this function would return an `exists T. T: Iterator` existential trait
1400 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1401 let def_id = tcx.parent(self.item_def_id);
1402 let subst_count = tcx.generics_of(def_id).count() - 1;
1403 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1404 ty::ExistentialTraitRef { def_id, substs }
1407 pub fn with_self_ty(
1411 ) -> ty::ProjectionPredicate<'tcx> {
1412 // otherwise the escaping regions would be captured by the binders
1413 debug_assert!(!self_ty.has_escaping_bound_vars());
1415 ty::ProjectionPredicate {
1416 projection_ty: ty::ProjectionTy {
1417 item_def_id: self.item_def_id,
1418 substs: tcx.mk_substs_trait(self_ty, self.substs),
1424 pub fn erase_self_ty(
1426 projection_predicate: ty::ProjectionPredicate<'tcx>,
1428 // Assert there is a Self.
1429 projection_predicate.projection_ty.substs.type_at(0);
1432 item_def_id: projection_predicate.projection_ty.item_def_id,
1433 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1434 term: projection_predicate.term,
1439 impl<'tcx> PolyExistentialProjection<'tcx> {
1440 pub fn with_self_ty(
1444 ) -> ty::PolyProjectionPredicate<'tcx> {
1445 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1448 pub fn item_def_id(&self) -> DefId {
1449 self.skip_binder().item_def_id
1453 /// Region utilities
1454 impl<'tcx> Region<'tcx> {
1455 pub fn kind(self) -> RegionKind<'tcx> {
1459 pub fn get_name(self) -> Option<Symbol> {
1460 if self.has_name() {
1461 let name = match *self {
1462 ty::ReEarlyBound(ebr) => Some(ebr.name),
1463 ty::ReLateBound(_, br) => br.kind.get_name(),
1464 ty::ReFree(fr) => fr.bound_region.get_name(),
1465 ty::ReStatic => Some(kw::StaticLifetime),
1466 ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
1476 /// Is this region named by the user?
1477 pub fn has_name(self) -> bool {
1479 ty::ReEarlyBound(ebr) => ebr.has_name(),
1480 ty::ReLateBound(_, br) => br.kind.is_named(),
1481 ty::ReFree(fr) => fr.bound_region.is_named(),
1482 ty::ReStatic => true,
1483 ty::ReVar(..) => false,
1484 ty::RePlaceholder(placeholder) => placeholder.name.is_named(),
1485 ty::ReErased => false,
1490 pub fn is_static(self) -> bool {
1491 matches!(*self, ty::ReStatic)
1495 pub fn is_erased(self) -> bool {
1496 matches!(*self, ty::ReErased)
1500 pub fn is_late_bound(self) -> bool {
1501 matches!(*self, ty::ReLateBound(..))
1505 pub fn is_placeholder(self) -> bool {
1506 matches!(*self, ty::RePlaceholder(..))
1510 pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
1512 ty::ReLateBound(debruijn, _) => debruijn >= index,
1517 pub fn type_flags(self) -> TypeFlags {
1518 let mut flags = TypeFlags::empty();
1522 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1523 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1524 flags = flags | TypeFlags::HAS_RE_INFER;
1526 ty::RePlaceholder(..) => {
1527 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1528 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1529 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1531 ty::ReEarlyBound(..) => {
1532 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1533 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1534 flags = flags | TypeFlags::HAS_RE_PARAM;
1536 ty::ReFree { .. } => {
1537 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1538 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1541 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1543 ty::ReLateBound(..) => {
1544 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1547 flags = flags | TypeFlags::HAS_RE_ERASED;
1551 debug!("type_flags({:?}) = {:?}", self, flags);
1556 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1557 /// For example, consider the regions in this snippet of code:
1559 /// ```ignore (illustrative)
1561 /// // ^^ -- early bound, declared on an impl
1563 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1564 /// // ^^ ^^ ^ anonymous, late-bound
1565 /// // | early-bound, appears in where-clauses
1566 /// // late-bound, appears only in fn args
1571 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1572 /// of the impl, and for all the other highlighted regions, it
1573 /// would return the `DefId` of the function. In other cases (not shown), this
1574 /// function might return the `DefId` of a closure.
1575 pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
1577 ty::ReEarlyBound(br) => tcx.parent(br.def_id),
1578 ty::ReFree(fr) => fr.scope,
1579 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1583 /// True for free regions other than `'static`.
1584 pub fn is_free(self) -> bool {
1585 matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
1588 /// True if `self` is a free region or static.
1589 pub fn is_free_or_static(self) -> bool {
1591 ty::ReStatic => true,
1592 _ => self.is_free(),
1596 pub fn is_var(self) -> bool {
1597 matches!(self.kind(), ty::ReVar(_))
1602 impl<'tcx> Ty<'tcx> {
1604 pub fn kind(self) -> &'tcx TyKind<'tcx> {
1609 pub fn flags(self) -> TypeFlags {
1614 pub fn is_unit(self) -> bool {
1616 Tuple(ref tys) => tys.is_empty(),
1622 pub fn is_never(self) -> bool {
1623 matches!(self.kind(), Never)
1627 pub fn is_primitive(self) -> bool {
1628 self.kind().is_primitive()
1632 pub fn is_adt(self) -> bool {
1633 matches!(self.kind(), Adt(..))
1637 pub fn is_ref(self) -> bool {
1638 matches!(self.kind(), Ref(..))
1642 pub fn is_ty_var(self) -> bool {
1643 matches!(self.kind(), Infer(TyVar(_)))
1647 pub fn ty_vid(self) -> Option<ty::TyVid> {
1649 &Infer(TyVar(vid)) => Some(vid),
1655 pub fn is_ty_infer(self) -> bool {
1656 matches!(self.kind(), Infer(_))
1660 pub fn is_phantom_data(self) -> bool {
1661 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1665 pub fn is_bool(self) -> bool {
1666 *self.kind() == Bool
1669 /// Returns `true` if this type is a `str`.
1671 pub fn is_str(self) -> bool {
1676 pub fn is_param(self, index: u32) -> bool {
1678 ty::Param(ref data) => data.index == index,
1684 pub fn is_slice(self) -> bool {
1685 matches!(self.kind(), Slice(_))
1689 pub fn is_array_slice(self) -> bool {
1692 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
1698 pub fn is_array(self) -> bool {
1699 matches!(self.kind(), Array(..))
1703 pub fn is_simd(self) -> bool {
1705 Adt(def, _) => def.repr().simd(),
1710 pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1712 Array(ty, _) | Slice(ty) => *ty,
1713 Str => tcx.types.u8,
1714 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1718 pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1720 Adt(def, substs) => {
1721 assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
1722 let variant = def.non_enum_variant();
1723 let f0_ty = variant.fields[0].ty(tcx, substs);
1725 match f0_ty.kind() {
1726 // If the first field is an array, we assume it is the only field and its
1727 // elements are the SIMD components.
1728 Array(f0_elem_ty, f0_len) => {
1729 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1730 // The way we evaluate the `N` in `[T; N]` here only works since we use
1731 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1732 // if we use it in generic code. See the `simd-array-trait` ui test.
1733 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty)
1735 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1736 // all have the same type).
1737 _ => (variant.fields.len() as u64, f0_ty),
1740 _ => bug!("`simd_size_and_type` called on invalid type"),
1745 pub fn is_region_ptr(self) -> bool {
1746 matches!(self.kind(), Ref(..))
1750 pub fn is_mutable_ptr(self) -> bool {
1753 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1754 | Ref(_, _, hir::Mutability::Mut)
1758 /// Get the mutability of the reference or `None` when not a reference
1760 pub fn ref_mutability(self) -> Option<hir::Mutability> {
1762 Ref(_, _, mutability) => Some(*mutability),
1768 pub fn is_unsafe_ptr(self) -> bool {
1769 matches!(self.kind(), RawPtr(_))
1772 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1774 pub fn is_any_ptr(self) -> bool {
1775 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1779 pub fn is_box(self) -> bool {
1781 Adt(def, _) => def.is_box(),
1786 /// Panics if called on any type other than `Box<T>`.
1787 pub fn boxed_ty(self) -> Ty<'tcx> {
1789 Adt(def, substs) if def.is_box() => substs.type_at(0),
1790 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1794 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1795 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1796 /// contents are abstract to rustc.)
1798 pub fn is_scalar(self) -> bool {
1808 | Infer(IntVar(_) | FloatVar(_))
1812 /// Returns `true` if this type is a floating point type.
1814 pub fn is_floating_point(self) -> bool {
1815 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1819 pub fn is_trait(self) -> bool {
1820 matches!(self.kind(), Dynamic(_, _, ty::Dyn))
1824 pub fn is_dyn_star(self) -> bool {
1825 matches!(self.kind(), Dynamic(_, _, ty::DynStar))
1829 pub fn is_enum(self) -> bool {
1830 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1834 pub fn is_union(self) -> bool {
1835 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1839 pub fn is_closure(self) -> bool {
1840 matches!(self.kind(), Closure(..))
1844 pub fn is_generator(self) -> bool {
1845 matches!(self.kind(), Generator(..))
1849 pub fn is_integral(self) -> bool {
1850 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
1854 pub fn is_fresh_ty(self) -> bool {
1855 matches!(self.kind(), Infer(FreshTy(_)))
1859 pub fn is_fresh(self) -> bool {
1860 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
1864 pub fn is_char(self) -> bool {
1865 matches!(self.kind(), Char)
1869 pub fn is_numeric(self) -> bool {
1870 self.is_integral() || self.is_floating_point()
1874 pub fn is_signed(self) -> bool {
1875 matches!(self.kind(), Int(_))
1879 pub fn is_ptr_sized_integral(self) -> bool {
1880 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
1884 pub fn has_concrete_skeleton(self) -> bool {
1885 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
1888 /// Checks whether a type recursively contains another type
1890 /// Example: `Option<()>` contains `()`
1891 pub fn contains(self, other: Ty<'tcx>) -> bool {
1892 struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
1894 impl<'tcx> TypeVisitor<'tcx> for ContainsTyVisitor<'tcx> {
1897 fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
1898 if self.0 == t { ControlFlow::BREAK } else { t.super_visit_with(self) }
1902 let cf = self.visit_with(&mut ContainsTyVisitor(other));
1906 /// Returns the type and mutability of `*ty`.
1908 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1909 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1910 pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1912 Adt(def, _) if def.is_box() => {
1913 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
1915 Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
1916 RawPtr(mt) if explicit => Some(*mt),
1921 /// Returns the type of `ty[i]`.
1922 pub fn builtin_index(self) -> Option<Ty<'tcx>> {
1924 Array(ty, _) | Slice(ty) => Some(*ty),
1929 pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
1931 FnDef(def_id, substs) => tcx.bound_fn_sig(*def_id).subst(tcx, substs),
1934 // ignore errors (#54954)
1935 ty::Binder::dummy(FnSig::fake())
1937 Closure(..) => bug!(
1938 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1940 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
1945 pub fn is_fn(self) -> bool {
1946 matches!(self.kind(), FnDef(..) | FnPtr(_))
1950 pub fn is_fn_ptr(self) -> bool {
1951 matches!(self.kind(), FnPtr(_))
1955 pub fn is_impl_trait(self) -> bool {
1956 matches!(self.kind(), Opaque(..))
1960 pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
1962 Adt(adt, _) => Some(*adt),
1967 /// Iterates over tuple fields.
1968 /// Panics when called on anything but a tuple.
1970 pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
1972 Tuple(substs) => substs,
1973 _ => bug!("tuple_fields called on non-tuple"),
1977 /// If the type contains variants, returns the valid range of variant indices.
1979 // FIXME: This requires the optimized MIR in the case of generators.
1981 pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
1983 TyKind::Adt(adt, _) => Some(adt.variant_range()),
1984 TyKind::Generator(def_id, substs, _) => {
1985 Some(substs.as_generator().variant_range(*def_id, tcx))
1991 /// If the type contains variants, returns the variant for `variant_index`.
1992 /// Panics if `variant_index` is out of range.
1994 // FIXME: This requires the optimized MIR in the case of generators.
1996 pub fn discriminant_for_variant(
1999 variant_index: VariantIdx,
2000 ) -> Option<Discr<'tcx>> {
2002 TyKind::Adt(adt, _) if adt.variants().is_empty() => {
2003 // This can actually happen during CTFE, see
2004 // https://github.com/rust-lang/rust/issues/89765.
2007 TyKind::Adt(adt, _) if adt.is_enum() => {
2008 Some(adt.discriminant_for_variant(tcx, variant_index))
2010 TyKind::Generator(def_id, substs, _) => {
2011 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2017 /// Returns the type of the discriminant of this type.
2018 pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2020 ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
2021 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2023 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2024 let assoc_items = tcx.associated_item_def_ids(
2025 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2027 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2046 | ty::GeneratorWitness(..)
2050 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2053 | ty::Placeholder(_)
2054 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2055 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2060 /// Returns the type of metadata for (potentially fat) pointers to this type,
2061 /// and a boolean signifying if this is conditional on this type being `Sized`.
2062 pub fn ptr_metadata_ty(
2065 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2066 ) -> (Ty<'tcx>, bool) {
2067 let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
2070 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2081 | ty::GeneratorWitness(..)
2086 // Extern types have metadata = ().
2088 // If returned by `struct_tail_without_normalization` this is a unit struct
2089 // without any fields, or not a struct, and therefore is Sized.
2091 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2092 // a.k.a. unit type, which is Sized
2093 | ty::Tuple(..) => (tcx.types.unit, false),
2095 ty::Str | ty::Slice(_) => (tcx.types.usize, false),
2096 ty::Dynamic(..) => {
2097 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2098 (tcx.bound_type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
2101 // type parameters only have unit metadata if they're sized, so return true
2102 // to make sure we double check this during confirmation
2103 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) => (tcx.types.unit, true),
2105 ty::Infer(ty::TyVar(_))
2107 | ty::Placeholder(..)
2108 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2109 bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
2114 /// When we create a closure, we record its kind (i.e., what trait
2115 /// it implements) into its `ClosureSubsts` using a type
2116 /// parameter. This is kind of a phantom type, except that the
2117 /// most convenient thing for us to are the integral types. This
2118 /// function converts such a special type into the closure
2119 /// kind. To go the other way, use
2120 /// `tcx.closure_kind_ty(closure_kind)`.
2122 /// Note that during type checking, we use an inference variable
2123 /// to represent the closure kind, because it has not yet been
2124 /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
2125 /// is complete, that type variable will be unified.
2126 pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
2128 Int(int_ty) => match int_ty {
2129 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2130 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2131 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2132 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2135 // "Bound" types appear in canonical queries when the
2136 // closure type is not yet known
2137 Bound(..) | Infer(_) => None,
2139 Error(_) => Some(ty::ClosureKind::Fn),
2141 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2145 /// Fast path helper for testing if a type is `Sized`.
2147 /// Returning true means the type is known to be sized. Returning
2148 /// `false` means nothing -- could be sized, might not be.
2150 /// Note that we could never rely on the fact that a type such as `[_]` is
2151 /// trivially `!Sized` because we could be in a type environment with a
2152 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2153 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2154 /// this method doesn't return `Option<bool>`.
2155 pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
2157 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2168 | ty::GeneratorWitness(..)
2172 | ty::Error(_) => true,
2174 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2176 ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2178 ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(),
2180 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2182 ty::Infer(ty::TyVar(_)) => false,
2185 | ty::Placeholder(..)
2186 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2187 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2192 /// Fast path helper for primitives which are always `Copy` and which
2193 /// have a side-effect-free `Clone` impl.
2195 /// Returning true means the type is known to be pure and `Copy+Clone`.
2196 /// Returning `false` means nothing -- could be `Copy`, might not be.
2198 /// This is mostly useful for optimizations, as there are the types
2199 /// on which we can replace cloning with dereferencing.
2200 pub fn is_trivially_pure_clone_copy(self) -> bool {
2202 ty::Bool | ty::Char | ty::Never => true,
2204 // These aren't even `Clone`
2205 ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
2207 ty::Int(..) | ty::Uint(..) | ty::Float(..) => true,
2209 // The voldemort ZSTs are fine.
2210 ty::FnDef(..) => true,
2212 ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
2214 // A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
2215 ty::Tuple(field_tys) => {
2216 field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
2219 // Sometimes traits aren't implemented for every ABI or arity,
2220 // because we can't be generic over everything yet.
2221 ty::FnPtr(..) => false,
2223 // Definitely absolutely not copy.
2224 ty::Ref(_, _, hir::Mutability::Mut) => false,
2226 // Thin pointers & thin shared references are pure-clone-copy, but for
2227 // anything with custom metadata it might be more complicated.
2228 ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
2230 ty::Generator(..) | ty::GeneratorWitness(..) => false,
2232 // Might be, but not "trivial" so just giving the safe answer.
2233 ty::Adt(..) | ty::Closure(..) | ty::Opaque(..) => false,
2235 ty::Projection(..) | ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
2237 ty::Bound(..) | ty::Placeholder(..) => {
2238 bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
2243 // If `self` is a primitive, return its [`Symbol`].
2244 pub fn primitive_symbol(self) -> Option<Symbol> {
2246 ty::Bool => Some(sym::bool),
2247 ty::Char => Some(sym::char),
2248 ty::Float(f) => match f {
2249 ty::FloatTy::F32 => Some(sym::f32),
2250 ty::FloatTy::F64 => Some(sym::f64),
2252 ty::Int(f) => match f {
2253 ty::IntTy::Isize => Some(sym::isize),
2254 ty::IntTy::I8 => Some(sym::i8),
2255 ty::IntTy::I16 => Some(sym::i16),
2256 ty::IntTy::I32 => Some(sym::i32),
2257 ty::IntTy::I64 => Some(sym::i64),
2258 ty::IntTy::I128 => Some(sym::i128),
2260 ty::Uint(f) => match f {
2261 ty::UintTy::Usize => Some(sym::usize),
2262 ty::UintTy::U8 => Some(sym::u8),
2263 ty::UintTy::U16 => Some(sym::u16),
2264 ty::UintTy::U32 => Some(sym::u32),
2265 ty::UintTy::U64 => Some(sym::u64),
2266 ty::UintTy::U128 => Some(sym::u128),
2273 /// Extra information about why we ended up with a particular variance.
2274 /// This is only used to add more information to error messages, and
2275 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2276 /// may lead to confusing notes in error messages, it will never cause
2277 /// a miscompilation or unsoundness.
2279 /// When in doubt, use `VarianceDiagInfo::default()`
2280 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2281 pub enum VarianceDiagInfo<'tcx> {
2282 /// No additional information - this is the default.
2283 /// We will not add any additional information to error messages.
2286 /// We switched our variance because a generic argument occurs inside
2287 /// the invariant generic argument of another type.
2289 /// The generic type containing the generic parameter
2290 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2292 /// The index of the generic parameter being used
2293 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2298 impl<'tcx> VarianceDiagInfo<'tcx> {
2299 /// Mirrors `Variance::xform` - used to 'combine' the existing
2300 /// and new `VarianceDiagInfo`s when our variance changes.
2301 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2302 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2304 VarianceDiagInfo::None => other,
2305 VarianceDiagInfo::Invariant { .. } => self,