//! This module contains `TyKind` and its major components. #![allow(rustc::usage_of_ty_tykind)] use crate::infer::canonical::Canonical; use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef}; use crate::ty::visit::ValidateBoundVars; use crate::ty::InferTy::*; use crate::ty::{ self, AdtDef, DefIdTree, Discr, FallibleTypeFolder, Term, Ty, TyCtxt, TypeFlags, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor, }; use crate::ty::{List, ParamEnv}; use hir::def::DefKind; use polonius_engine::Atom; use rustc_data_structures::captures::Captures; use rustc_data_structures::intern::Interned; use rustc_hir as hir; use rustc_hir::def_id::DefId; use rustc_hir::LangItem; use rustc_index::vec::Idx; use rustc_macros::HashStable; use rustc_span::symbol::{kw, sym, Symbol}; use rustc_span::Span; use rustc_target::abi::VariantIdx; use rustc_target::spec::abi; use std::borrow::Cow; use std::cmp::Ordering; use std::fmt; use std::marker::PhantomData; use std::ops::{ControlFlow, Deref, Range}; use ty::util::IntTypeExt; use rustc_type_ir::sty::TyKind::*; use rustc_type_ir::RegionKind as IrRegionKind; use rustc_type_ir::TyKind as IrTyKind; // Re-export the `TyKind` from `rustc_type_ir` here for convenience #[rustc_diagnostic_item = "TyKind"] pub type TyKind<'tcx> = IrTyKind>; pub type RegionKind<'tcx> = IrRegionKind>; #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct TypeAndMut<'tcx> { pub ty: Ty<'tcx>, pub mutbl: hir::Mutability, } #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)] #[derive(HashStable)] /// A "free" region `fr` can be interpreted as "some region /// at least as big as the scope `fr.scope`". pub struct FreeRegion { pub scope: DefId, pub bound_region: BoundRegionKind, } #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)] #[derive(HashStable)] pub enum BoundRegionKind { /// An anonymous region parameter for a given fn (&T) BrAnon(u32, Option), /// Named region parameters for functions (a in &'a T) /// /// The `DefId` is needed to distinguish free regions in /// the event of shadowing. BrNamed(DefId, Symbol), /// Anonymous region for the implicit env pointer parameter /// to a closure BrEnv, } #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)] #[derive(HashStable)] pub struct BoundRegion { pub var: BoundVar, pub kind: BoundRegionKind, } impl BoundRegionKind { pub fn is_named(&self) -> bool { match *self { BoundRegionKind::BrNamed(_, name) => { name != kw::UnderscoreLifetime && name != kw::Empty } _ => false, } } pub fn get_name(&self) -> Option { if self.is_named() { match *self { BoundRegionKind::BrNamed(_, name) => return Some(name), _ => unreachable!(), } } None } pub fn get_id(&self) -> Option { match *self { BoundRegionKind::BrNamed(id, _) => return Some(id), _ => None, } } pub fn expect_anon(&self) -> u32 { match *self { BoundRegionKind::BrNamed(_, _) | BoundRegionKind::BrEnv => { bug!("expected anon region: {self:?}") } BoundRegionKind::BrAnon(idx, _) => idx, } } } pub trait Article { fn article(&self) -> &'static str; } impl<'tcx> Article for TyKind<'tcx> { /// Get the article ("a" or "an") to use with this type. fn article(&self) -> &'static str { match self { Int(_) | Float(_) | Array(_, _) => "an", Adt(def, _) if def.is_enum() => "an", // This should never happen, but ICEing and causing the user's code // to not compile felt too harsh. Error(_) => "a", _ => "a", } } } // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger. #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] static_assert_size!(TyKind<'_>, 32); /// A closure can be modeled as a struct that looks like: /// ```ignore (illustrative) /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U); /// ``` /// where: /// /// - 'l0...'li and T0...Tj are the generic parameters /// in scope on the function that defined the closure, /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This /// is rather hackily encoded via a scalar type. See /// `Ty::to_opt_closure_kind` for details. /// - CS represents the *closure signature*, representing as a `fn()` /// type. For example, `fn(u32, u32) -> u32` would mean that the closure /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait /// specified above. /// - U is a type parameter representing the types of its upvars, tupled up /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar, /// and the up-var has the type `Foo`, then that field of U will be `&Foo`). /// /// So, for example, given this function: /// ```ignore (illustrative) /// fn foo<'a, T>(data: &'a mut T) { /// do(|| data.count += 1) /// } /// ``` /// the type of the closure would be something like: /// ```ignore (illustrative) /// struct Closure<'a, T, U>(...U); /// ``` /// Note that the type of the upvar is not specified in the struct. /// You may wonder how the impl would then be able to use the upvar, /// if it doesn't know it's type? The answer is that the impl is /// (conceptually) not fully generic over Closure but rather tied to /// instances with the expected upvar types: /// ```ignore (illustrative) /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> { /// ... /// } /// ``` /// You can see that the *impl* fully specified the type of the upvar /// and thus knows full well that `data` has type `&'b mut &'a mut T`. /// (Here, I am assuming that `data` is mut-borrowed.) /// /// Now, the last question you may ask is: Why include the upvar types /// in an extra type parameter? The reason for this design is that the /// upvar types can reference lifetimes that are internal to the /// creating function. In my example above, for example, the lifetime /// `'b` represents the scope of the closure itself; this is some /// subset of `foo`, probably just the scope of the call to the to /// `do()`. If we just had the lifetime/type parameters from the /// enclosing function, we couldn't name this lifetime `'b`. Note that /// there can also be lifetimes in the types of the upvars themselves, /// if one of them happens to be a reference to something that the /// creating fn owns. /// /// OK, you say, so why not create a more minimal set of parameters /// that just includes the extra lifetime parameters? The answer is /// primarily that it would be hard --- we don't know at the time when /// we create the closure type what the full types of the upvars are, /// nor do we know which are borrowed and which are not. In this /// design, we can just supply a fresh type parameter and figure that /// out later. /// /// All right, you say, but why include the type parameters from the /// original function then? The answer is that codegen may need them /// when monomorphizing, and they may not appear in the upvars. A /// closure could capture no variables but still make use of some /// in-scope type parameter with a bound (e.g., if our example above /// had an extra `U: Default`, and the closure called `U::default()`). /// /// There is another reason. This design (implicitly) prohibits /// closures from capturing themselves (except via a trait /// object). This simplifies closure inference considerably, since it /// means that when we infer the kind of a closure or its upvars, we /// don't have to handle cycles where the decisions we make for /// closure C wind up influencing the decisions we ought to make for /// closure C (which would then require fixed point iteration to /// handle). Plus it fixes an ICE. :P /// /// ## Generators /// /// Generators are handled similarly in `GeneratorSubsts`. The set of /// type parameters is similar, but `CK` and `CS` are replaced by the /// following type parameters: /// /// * `GS`: The generator's "resume type", which is the type of the /// argument passed to `resume`, and the type of `yield` expressions /// inside the generator. /// * `GY`: The "yield type", which is the type of values passed to /// `yield` inside the generator. /// * `GR`: The "return type", which is the type of value returned upon /// completion of the generator. /// * `GW`: The "generator witness". #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable, Lift)] pub struct ClosureSubsts<'tcx> { /// Lifetime and type parameters from the enclosing function, /// concatenated with a tuple containing the types of the upvars. /// /// These are separated out because codegen wants to pass them around /// when monomorphizing. pub substs: SubstsRef<'tcx>, } /// Struct returned by `split()`. pub struct ClosureSubstsParts<'tcx, T> { pub parent_substs: &'tcx [GenericArg<'tcx>], pub closure_kind_ty: T, pub closure_sig_as_fn_ptr_ty: T, pub tupled_upvars_ty: T, } impl<'tcx> ClosureSubsts<'tcx> { /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs` /// for the closure parent, alongside additional closure-specific components. pub fn new( tcx: TyCtxt<'tcx>, parts: ClosureSubstsParts<'tcx, Ty<'tcx>>, ) -> ClosureSubsts<'tcx> { ClosureSubsts { substs: tcx.mk_substs_from_iter( parts.parent_substs.iter().copied().chain( [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty] .iter() .map(|&ty| ty.into()), ), ), } } /// Divides the closure substs into their respective components. /// The ordering assumed here must match that used by `ClosureSubsts::new` above. fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> { match self.substs[..] { [ ref parent_substs @ .., closure_kind_ty, closure_sig_as_fn_ptr_ty, tupled_upvars_ty, ] => ClosureSubstsParts { parent_substs, closure_kind_ty, closure_sig_as_fn_ptr_ty, tupled_upvars_ty, }, _ => bug!("closure substs missing synthetics"), } } /// Returns `true` only if enough of the synthetic types are known to /// allow using all of the methods on `ClosureSubsts` without panicking. /// /// Used primarily by `ty::print::pretty` to be able to handle closure /// types that haven't had their synthetic types substituted in. pub fn is_valid(self) -> bool { self.substs.len() >= 3 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_)) } /// Returns the substitutions of the closure's parent. pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] { self.split().parent_substs } /// Returns an iterator over the list of types of captured paths by the closure. /// In case there was a type error in figuring out the types of the captured path, an /// empty iterator is returned. #[inline] pub fn upvar_tys(self) -> impl Iterator> + 'tcx { match self.tupled_upvars_ty().kind() { TyKind::Error(_) => None, TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()), TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"), ty => bug!("Unexpected representation of upvar types tuple {:?}", ty), } .into_iter() .flatten() } /// Returns the tuple type representing the upvars for this closure. #[inline] pub fn tupled_upvars_ty(self) -> Ty<'tcx> { self.split().tupled_upvars_ty.expect_ty() } /// Returns the closure kind for this closure; may return a type /// variable during inference. To get the closure kind during /// inference, use `infcx.closure_kind(substs)`. pub fn kind_ty(self) -> Ty<'tcx> { self.split().closure_kind_ty.expect_ty() } /// Returns the `fn` pointer type representing the closure signature for this /// closure. // FIXME(eddyb) this should be unnecessary, as the shallowly resolved // type is known at the time of the creation of `ClosureSubsts`, // see `rustc_hir_analysis::check::closure`. pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> { self.split().closure_sig_as_fn_ptr_ty.expect_ty() } /// Returns the closure kind for this closure; only usable outside /// of an inference context, because in that context we know that /// there are no type variables. /// /// If you have an inference context, use `infcx.closure_kind()`. pub fn kind(self) -> ty::ClosureKind { self.kind_ty().to_opt_closure_kind().unwrap() } /// Extracts the signature from the closure. pub fn sig(self) -> ty::PolyFnSig<'tcx> { let ty = self.sig_as_fn_ptr_ty(); match ty.kind() { ty::FnPtr(sig) => *sig, _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()), } } pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> { ty::print::PrintClosureAsImpl { closure: self } } } /// Similar to `ClosureSubsts`; see the above documentation for more. #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable, Lift)] pub struct GeneratorSubsts<'tcx> { pub substs: SubstsRef<'tcx>, } pub struct GeneratorSubstsParts<'tcx, T> { pub parent_substs: &'tcx [GenericArg<'tcx>], pub resume_ty: T, pub yield_ty: T, pub return_ty: T, pub witness: T, pub tupled_upvars_ty: T, } impl<'tcx> GeneratorSubsts<'tcx> { /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs` /// for the generator parent, alongside additional generator-specific components. pub fn new( tcx: TyCtxt<'tcx>, parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>, ) -> GeneratorSubsts<'tcx> { GeneratorSubsts { substs: tcx.mk_substs_from_iter( parts.parent_substs.iter().copied().chain( [ parts.resume_ty, parts.yield_ty, parts.return_ty, parts.witness, parts.tupled_upvars_ty, ] .iter() .map(|&ty| ty.into()), ), ), } } /// Divides the generator substs into their respective components. /// The ordering assumed here must match that used by `GeneratorSubsts::new` above. fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> { match self.substs[..] { [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => { GeneratorSubstsParts { parent_substs, resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty, } } _ => bug!("generator substs missing synthetics"), } } /// Returns `true` only if enough of the synthetic types are known to /// allow using all of the methods on `GeneratorSubsts` without panicking. /// /// Used primarily by `ty::print::pretty` to be able to handle generator /// types that haven't had their synthetic types substituted in. pub fn is_valid(self) -> bool { self.substs.len() >= 5 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_)) } /// Returns the substitutions of the generator's parent. pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] { self.split().parent_substs } /// This describes the types that can be contained in a generator. /// It will be a type variable initially and unified in the last stages of typeck of a body. /// It contains a tuple of all the types that could end up on a generator frame. /// The state transformation MIR pass may only produce layouts which mention types /// in this tuple. Upvars are not counted here. pub fn witness(self) -> Ty<'tcx> { self.split().witness.expect_ty() } /// Returns an iterator over the list of types of captured paths by the generator. /// In case there was a type error in figuring out the types of the captured path, an /// empty iterator is returned. #[inline] pub fn upvar_tys(self) -> impl Iterator> + 'tcx { match self.tupled_upvars_ty().kind() { TyKind::Error(_) => None, TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()), TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"), ty => bug!("Unexpected representation of upvar types tuple {:?}", ty), } .into_iter() .flatten() } /// Returns the tuple type representing the upvars for this generator. #[inline] pub fn tupled_upvars_ty(self) -> Ty<'tcx> { self.split().tupled_upvars_ty.expect_ty() } /// Returns the type representing the resume type of the generator. pub fn resume_ty(self) -> Ty<'tcx> { self.split().resume_ty.expect_ty() } /// Returns the type representing the yield type of the generator. pub fn yield_ty(self) -> Ty<'tcx> { self.split().yield_ty.expect_ty() } /// Returns the type representing the return type of the generator. pub fn return_ty(self) -> Ty<'tcx> { self.split().return_ty.expect_ty() } /// Returns the "generator signature", which consists of its yield /// and return types. /// /// N.B., some bits of the code prefers to see this wrapped in a /// binder, but it never contains bound regions. Probably this /// function should be removed. pub fn poly_sig(self) -> PolyGenSig<'tcx> { ty::Binder::dummy(self.sig()) } /// Returns the "generator signature", which consists of its resume, yield /// and return types. pub fn sig(self) -> GenSig<'tcx> { ty::GenSig { resume_ty: self.resume_ty(), yield_ty: self.yield_ty(), return_ty: self.return_ty(), } } } impl<'tcx> GeneratorSubsts<'tcx> { /// Generator has not been resumed yet. pub const UNRESUMED: usize = 0; /// Generator has returned or is completed. pub const RETURNED: usize = 1; /// Generator has been poisoned. pub const POISONED: usize = 2; const UNRESUMED_NAME: &'static str = "Unresumed"; const RETURNED_NAME: &'static str = "Returned"; const POISONED_NAME: &'static str = "Panicked"; /// The valid variant indices of this generator. #[inline] pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range { // FIXME requires optimized MIR let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len(); VariantIdx::new(0)..VariantIdx::new(num_variants) } /// The discriminant for the given variant. Panics if the `variant_index` is /// out of range. #[inline] pub fn discriminant_for_variant( &self, def_id: DefId, tcx: TyCtxt<'tcx>, variant_index: VariantIdx, ) -> Discr<'tcx> { // Generators don't support explicit discriminant values, so they are // the same as the variant index. assert!(self.variant_range(def_id, tcx).contains(&variant_index)); Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) } } /// The set of all discriminants for the generator, enumerated with their /// variant indices. #[inline] pub fn discriminants( self, def_id: DefId, tcx: TyCtxt<'tcx>, ) -> impl Iterator)> + Captures<'tcx> { self.variant_range(def_id, tcx).map(move |index| { (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) }) }) } /// Calls `f` with a reference to the name of the enumerator for the given /// variant `v`. pub fn variant_name(v: VariantIdx) -> Cow<'static, str> { match v.as_usize() { Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME), Self::RETURNED => Cow::from(Self::RETURNED_NAME), Self::POISONED => Cow::from(Self::POISONED_NAME), _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)), } } /// The type of the state discriminant used in the generator type. #[inline] pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { tcx.types.u32 } /// This returns the types of the MIR locals which had to be stored across suspension points. /// It is calculated in rustc_mir_transform::generator::StateTransform. /// All the types here must be in the tuple in GeneratorInterior. /// /// The locals are grouped by their variant number. Note that some locals may /// be repeated in multiple variants. #[inline] pub fn state_tys( self, def_id: DefId, tcx: TyCtxt<'tcx>, ) -> impl Iterator> + Captures<'tcx>> { let layout = tcx.generator_layout(def_id).unwrap(); layout.variant_fields.iter().map(move |variant| { variant.iter().map(move |field| { ty::EarlyBinder(layout.field_tys[*field].ty).subst(tcx, self.substs) }) }) } /// This is the types of the fields of a generator which are not stored in a /// variant. #[inline] pub fn prefix_tys(self) -> impl Iterator> { self.upvar_tys() } } #[derive(Debug, Copy, Clone, HashStable)] pub enum UpvarSubsts<'tcx> { Closure(SubstsRef<'tcx>), Generator(SubstsRef<'tcx>), } impl<'tcx> UpvarSubsts<'tcx> { /// Returns an iterator over the list of types of captured paths by the closure/generator. /// In case there was a type error in figuring out the types of the captured path, an /// empty iterator is returned. #[inline] pub fn upvar_tys(self) -> impl Iterator> + 'tcx { let tupled_tys = match self { UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(), UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(), }; match tupled_tys.kind() { TyKind::Error(_) => None, TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()), TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"), ty => bug!("Unexpected representation of upvar types tuple {:?}", ty), } .into_iter() .flatten() } #[inline] pub fn tupled_upvars_ty(self) -> Ty<'tcx> { match self { UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(), UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(), } } } /// An inline const is modeled like /// ```ignore (illustrative) /// const InlineConst<'l0...'li, T0...Tj, R>: R; /// ``` /// where: /// /// - 'l0...'li and T0...Tj are the generic parameters /// inherited from the item that defined the inline const, /// - R represents the type of the constant. /// /// When the inline const is instantiated, `R` is substituted as the actual inferred /// type of the constant. The reason that `R` is represented as an extra type parameter /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters: /// inline const can reference lifetimes that are internal to the creating function. #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)] pub struct InlineConstSubsts<'tcx> { /// Generic parameters from the enclosing item, /// concatenated with the inferred type of the constant. pub substs: SubstsRef<'tcx>, } /// Struct returned by `split()`. pub struct InlineConstSubstsParts<'tcx, T> { pub parent_substs: &'tcx [GenericArg<'tcx>], pub ty: T, } impl<'tcx> InlineConstSubsts<'tcx> { /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`. pub fn new( tcx: TyCtxt<'tcx>, parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>, ) -> InlineConstSubsts<'tcx> { InlineConstSubsts { substs: tcx.mk_substs_from_iter( parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())), ), } } /// Divides the inline const substs into their respective components. /// The ordering assumed here must match that used by `InlineConstSubsts::new` above. fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> { match self.substs[..] { [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty }, _ => bug!("inline const substs missing synthetics"), } } /// Returns the substitutions of the inline const's parent. pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] { self.split().parent_substs } /// Returns the type of this inline const. pub fn ty(self) -> Ty<'tcx> { self.split().ty.expect_ty() } } #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub enum ExistentialPredicate<'tcx> { /// E.g., `Iterator`. Trait(ExistentialTraitRef<'tcx>), /// E.g., `Iterator::Item = T`. Projection(ExistentialProjection<'tcx>), /// E.g., `Send`. AutoTrait(DefId), } impl<'tcx> ExistentialPredicate<'tcx> { /// Compares via an ordering that will not change if modules are reordered or other changes are /// made to the tree. In particular, this ordering is preserved across incremental compilations. pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering { use self::ExistentialPredicate::*; match (*self, *other) { (Trait(_), Trait(_)) => Ordering::Equal, (Projection(ref a), Projection(ref b)) => { tcx.def_path_hash(a.def_id).cmp(&tcx.def_path_hash(b.def_id)) } (AutoTrait(ref a), AutoTrait(ref b)) => { tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b)) } (Trait(_), _) => Ordering::Less, (Projection(_), Trait(_)) => Ordering::Greater, (Projection(_), _) => Ordering::Less, (AutoTrait(_), _) => Ordering::Greater, } } } pub type PolyExistentialPredicate<'tcx> = Binder<'tcx, ExistentialPredicate<'tcx>>; impl<'tcx> PolyExistentialPredicate<'tcx> { /// Given an existential predicate like `?Self: PartialEq` (e.g., derived from `dyn PartialEq`), /// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self` /// has been replaced with `self_ty` (e.g., `self_ty: PartialEq`, in our example). pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> { use crate::ty::ToPredicate; match self.skip_binder() { ExistentialPredicate::Trait(tr) => { self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx) } ExistentialPredicate::Projection(p) => { self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx) } ExistentialPredicate::AutoTrait(did) => { let generics = tcx.generics_of(did); let trait_ref = if generics.params.len() == 1 { tcx.mk_trait_ref(did, [self_ty]) } else { // If this is an ill-formed auto trait, then synthesize // new error substs for the missing generics. let err_substs = ty::InternalSubsts::extend_with_error(tcx, did, &[self_ty.into()]); tcx.mk_trait_ref(did, err_substs) }; self.rebind(trait_ref).without_const().to_predicate(tcx) } } } } impl<'tcx> List> { /// Returns the "principal `DefId`" of this set of existential predicates. /// /// A Rust trait object type consists (in addition to a lifetime bound) /// of a set of trait bounds, which are separated into any number /// of auto-trait bounds, and at most one non-auto-trait bound. The /// non-auto-trait bound is called the "principal" of the trait /// object. /// /// Only the principal can have methods or type parameters (because /// auto traits can have neither of them). This is important, because /// it means the auto traits can be treated as an unordered set (methods /// would force an order for the vtable, while relating traits with /// type parameters without knowing the order to relate them in is /// a rather non-trivial task). /// /// For example, in the trait object `dyn fmt::Debug + Sync`, the /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds /// are the set `{Sync}`. /// /// It is also possible to have a "trivial" trait object that /// consists only of auto traits, with no principal - for example, /// `dyn Send + Sync`. In that case, the set of auto-trait bounds /// is `{Send, Sync}`, while there is no principal. These trait objects /// have a "trivial" vtable consisting of just the size, alignment, /// and destructor. pub fn principal(&self) -> Option>> { self[0] .map_bound(|this| match this { ExistentialPredicate::Trait(tr) => Some(tr), _ => None, }) .transpose() } pub fn principal_def_id(&self) -> Option { self.principal().map(|trait_ref| trait_ref.skip_binder().def_id) } #[inline] pub fn projection_bounds<'a>( &'a self, ) -> impl Iterator>> + 'a { self.iter().filter_map(|predicate| { predicate .map_bound(|pred| match pred { ExistentialPredicate::Projection(projection) => Some(projection), _ => None, }) .transpose() }) } #[inline] pub fn auto_traits<'a>(&'a self) -> impl Iterator + Captures<'tcx> + 'a { self.iter().filter_map(|predicate| match predicate.skip_binder() { ExistentialPredicate::AutoTrait(did) => Some(did), _ => None, }) } } /// A complete reference to a trait. These take numerous guises in syntax, /// but perhaps the most recognizable form is in a where-clause: /// ```ignore (illustrative) /// T: Foo /// ``` /// This would be represented by a trait-reference where the `DefId` is the /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0, /// and `U` as parameter 1. /// /// Trait references also appear in object types like `Foo`, but in /// that case the `Self` parameter is absent from the substitutions. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct TraitRef<'tcx> { pub def_id: DefId, pub substs: SubstsRef<'tcx>, /// This field exists to prevent the creation of `TraitRef` without /// calling [TyCtxt::mk_trait_ref]. pub(super) _use_mk_trait_ref_instead: (), } impl<'tcx> TraitRef<'tcx> { pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self { tcx.mk_trait_ref( self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter().skip(1)), ) } /// Returns a `TraitRef` of the form `P0: Foo` where `Pi` /// are the parameters defined on trait. pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> { ty::Binder::dummy(tcx.mk_trait_ref(def_id, InternalSubsts::identity_for_item(tcx, def_id))) } #[inline] pub fn self_ty(&self) -> Ty<'tcx> { self.substs.type_at(0) } pub fn from_method( tcx: TyCtxt<'tcx>, trait_id: DefId, substs: SubstsRef<'tcx>, ) -> ty::TraitRef<'tcx> { let defs = tcx.generics_of(trait_id); tcx.mk_trait_ref(trait_id, tcx.mk_substs(&substs[..defs.params.len()])) } } pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>; impl<'tcx> PolyTraitRef<'tcx> { pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> { self.map_bound_ref(|tr| tr.self_ty()) } pub fn def_id(&self) -> DefId { self.skip_binder().def_id } } impl rustc_errors::IntoDiagnosticArg for PolyTraitRef<'_> { fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> { self.to_string().into_diagnostic_arg() } } /// An existential reference to a trait, where `Self` is erased. /// For example, the trait object `Trait<'a, 'b, X, Y>` is: /// ```ignore (illustrative) /// exists T. T: Trait<'a, 'b, X, Y> /// ``` /// The substitutions don't include the erased `Self`, only trait /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above). #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct ExistentialTraitRef<'tcx> { pub def_id: DefId, pub substs: SubstsRef<'tcx>, } impl<'tcx> ExistentialTraitRef<'tcx> { pub fn erase_self_ty( tcx: TyCtxt<'tcx>, trait_ref: ty::TraitRef<'tcx>, ) -> ty::ExistentialTraitRef<'tcx> { // Assert there is a Self. trait_ref.substs.type_at(0); ty::ExistentialTraitRef { def_id: trait_ref.def_id, substs: tcx.mk_substs(&trait_ref.substs[1..]), } } /// Object types don't have a self type specified. Therefore, when /// we convert the principal trait-ref into a normal trait-ref, /// you must give *some* self type. A common choice is `mk_err()` /// or some placeholder type. pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> { // otherwise the escaping vars would be captured by the binder // debug_assert!(!self_ty.has_escaping_bound_vars()); tcx.mk_trait_ref(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter())) } } pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>; impl<'tcx> PolyExistentialTraitRef<'tcx> { pub fn def_id(&self) -> DefId { self.skip_binder().def_id } /// Object types don't have a self type specified. Therefore, when /// we convert the principal trait-ref into a normal trait-ref, /// you must give *some* self type. A common choice is `mk_err()` /// or some placeholder type. pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> { self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty)) } } impl rustc_errors::IntoDiagnosticArg for PolyExistentialTraitRef<'_> { fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> { self.to_string().into_diagnostic_arg() } } #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable)] pub enum BoundVariableKind { Ty(BoundTyKind), Region(BoundRegionKind), Const, } impl BoundVariableKind { pub fn expect_region(self) -> BoundRegionKind { match self { BoundVariableKind::Region(lt) => lt, _ => bug!("expected a region, but found another kind"), } } pub fn expect_ty(self) -> BoundTyKind { match self { BoundVariableKind::Ty(ty) => ty, _ => bug!("expected a type, but found another kind"), } } pub fn expect_const(self) { match self { BoundVariableKind::Const => (), _ => bug!("expected a const, but found another kind"), } } } /// Binder is a binder for higher-ranked lifetimes or types. It is part of the /// compiler's representation for things like `for<'a> Fn(&'a isize)` /// (which would be represented by the type `PolyTraitRef == /// Binder<'tcx, TraitRef>`). Note that when we instantiate, /// erase, or otherwise "discharge" these bound vars, we change the /// type from `Binder<'tcx, T>` to just `T` (see /// e.g., `liberate_late_bound_regions`). /// /// `Decodable` and `Encodable` are implemented for `Binder` using the `impl_binder_encode_decode!` macro. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] #[derive(HashStable, Lift)] pub struct Binder<'tcx, T>(T, &'tcx List); impl<'tcx, T> Binder<'tcx, T> where T: TypeVisitable>, { /// Wraps `value` in a binder, asserting that `value` does not /// contain any bound vars that would be bound by the /// binder. This is commonly used to 'inject' a value T into a /// different binding level. #[track_caller] pub fn dummy(value: T) -> Binder<'tcx, T> { assert!( !value.has_escaping_bound_vars(), "`{value:?}` has escaping bound vars, so it cannot be wrapped in a dummy binder." ); Binder(value, ty::List::empty()) } pub fn bind_with_vars(value: T, vars: &'tcx List) -> Binder<'tcx, T> { if cfg!(debug_assertions) { let mut validator = ValidateBoundVars::new(vars); value.visit_with(&mut validator); } Binder(value, vars) } } impl<'tcx, T> Binder<'tcx, T> { /// Skips the binder and returns the "bound" value. This is a /// risky thing to do because it's easy to get confused about /// De Bruijn indices and the like. It is usually better to /// discharge the binder using `no_bound_vars` or /// `replace_late_bound_regions` or something like /// that. `skip_binder` is only valid when you are either /// extracting data that has nothing to do with bound vars, you /// are doing some sort of test that does not involve bound /// regions, or you are being very careful about your depth /// accounting. /// /// Some examples where `skip_binder` is reasonable: /// /// - extracting the `DefId` from a PolyTraitRef; /// - comparing the self type of a PolyTraitRef to see if it is equal to /// a type parameter `X`, since the type `X` does not reference any regions pub fn skip_binder(self) -> T { self.0 } pub fn bound_vars(&self) -> &'tcx List { self.1 } pub fn as_ref(&self) -> Binder<'tcx, &T> { Binder(&self.0, self.1) } pub fn as_deref(&self) -> Binder<'tcx, &T::Target> where T: Deref, { Binder(&self.0, self.1) } pub fn map_bound_ref_unchecked(&self, f: F) -> Binder<'tcx, U> where F: FnOnce(&T) -> U, { let value = f(&self.0); Binder(value, self.1) } pub fn map_bound_ref>>(&self, f: F) -> Binder<'tcx, U> where F: FnOnce(&T) -> U, { self.as_ref().map_bound(f) } pub fn map_bound>>(self, f: F) -> Binder<'tcx, U> where F: FnOnce(T) -> U, { let value = f(self.0); if cfg!(debug_assertions) { let mut validator = ValidateBoundVars::new(self.1); value.visit_with(&mut validator); } Binder(value, self.1) } pub fn try_map_bound>, E>( self, f: F, ) -> Result, E> where F: FnOnce(T) -> Result, { let value = f(self.0)?; if cfg!(debug_assertions) { let mut validator = ValidateBoundVars::new(self.1); value.visit_with(&mut validator); } Ok(Binder(value, self.1)) } /// Wraps a `value` in a binder, using the same bound variables as the /// current `Binder`. This should not be used if the new value *changes* /// the bound variables. Note: the (old or new) value itself does not /// necessarily need to *name* all the bound variables. /// /// This currently doesn't do anything different than `bind`, because we /// don't actually track bound vars. However, semantically, it is different /// because bound vars aren't allowed to change here, whereas they are /// in `bind`. This may be (debug) asserted in the future. pub fn rebind(&self, value: U) -> Binder<'tcx, U> where U: TypeVisitable>, { if cfg!(debug_assertions) { let mut validator = ValidateBoundVars::new(self.bound_vars()); value.visit_with(&mut validator); } Binder(value, self.1) } /// Unwraps and returns the value within, but only if it contains /// no bound vars at all. (In other words, if this binder -- /// and indeed any enclosing binder -- doesn't bind anything at /// all.) Otherwise, returns `None`. /// /// (One could imagine having a method that just unwraps a single /// binder, but permits late-bound vars bound by enclosing /// binders, but that would require adjusting the debruijn /// indices, and given the shallow binding structure we often use, /// would not be that useful.) pub fn no_bound_vars(self) -> Option where T: TypeVisitable>, { if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) } } /// Splits the contents into two things that share the same binder /// level as the original, returning two distinct binders. /// /// `f` should consider bound regions at depth 1 to be free, and /// anything it produces with bound regions at depth 1 will be /// bound in the resulting return values. pub fn split(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>) where F: FnOnce(T) -> (U, V), { let (u, v) = f(self.0); (Binder(u, self.1), Binder(v, self.1)) } } impl<'tcx, T> Binder<'tcx, Option> { pub fn transpose(self) -> Option> { let bound_vars = self.1; self.0.map(|v| Binder(v, bound_vars)) } } impl<'tcx, T: IntoIterator> Binder<'tcx, T> { pub fn iter(self) -> impl Iterator> { let bound_vars = self.1; self.0.into_iter().map(|v| Binder(v, bound_vars)) } } struct SkipBindersAt<'tcx> { tcx: TyCtxt<'tcx>, index: ty::DebruijnIndex, } impl<'tcx> FallibleTypeFolder> for SkipBindersAt<'tcx> { type Error = (); fn interner(&self) -> TyCtxt<'tcx> { self.tcx } fn try_fold_binder(&mut self, t: Binder<'tcx, T>) -> Result, Self::Error> where T: ty::TypeFoldable>, { self.index.shift_in(1); let value = t.try_map_bound(|t| t.try_fold_with(self)); self.index.shift_out(1); value } fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result, Self::Error> { if !ty.has_escaping_bound_vars() { Ok(ty) } else if let ty::Bound(index, bv) = *ty.kind() { if index == self.index { Err(()) } else { Ok(self.interner().mk_bound(index.shifted_out(1), bv)) } } else { ty.try_super_fold_with(self) } } fn try_fold_region(&mut self, r: ty::Region<'tcx>) -> Result, Self::Error> { if !r.has_escaping_bound_vars() { Ok(r) } else if let ty::ReLateBound(index, bv) = r.kind() { if index == self.index { Err(()) } else { Ok(self.interner().mk_re_late_bound(index.shifted_out(1), bv)) } } else { r.try_super_fold_with(self) } } fn try_fold_const(&mut self, ct: ty::Const<'tcx>) -> Result, Self::Error> { if !ct.has_escaping_bound_vars() { Ok(ct) } else if let ty::ConstKind::Bound(index, bv) = ct.kind() { if index == self.index { Err(()) } else { Ok(self.interner().mk_const( ty::ConstKind::Bound(index.shifted_out(1), bv), ct.ty().try_fold_with(self)?, )) } } else { ct.try_super_fold_with(self) } } fn try_fold_predicate( &mut self, p: ty::Predicate<'tcx>, ) -> Result, Self::Error> { if !p.has_escaping_bound_vars() { Ok(p) } else { p.try_super_fold_with(self) } } } /// Represents the projection of an associated type. /// /// For a projection, this would be `>::N`. /// /// For an opaque type, there is no explicit syntax. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct AliasTy<'tcx> { /// The parameters of the associated or opaque item. /// /// For a projection, these are the substitutions for the trait and the /// GAT substitutions, if there are any. /// /// For RPIT the substitutions are for the generics of the function, /// while for TAIT it is used for the generic parameters of the alias. pub substs: SubstsRef<'tcx>, /// The `DefId` of the `TraitItem` for the associated type `N` if this is a projection, /// or the `OpaqueType` item if this is an opaque. /// /// During codegen, `tcx.type_of(def_id)` can be used to get the type of the /// underlying type if the type is an opaque. /// /// Note that if this is an associated type, this is not the `DefId` of the /// `TraitRef` containing this associated type, which is in `tcx.associated_item(def_id).container`, /// aka. `tcx.parent(def_id)`. pub def_id: DefId, /// This field exists to prevent the creation of `AliasTy` without using /// [TyCtxt::mk_alias_ty]. pub(super) _use_mk_alias_ty_instead: (), } impl<'tcx> AliasTy<'tcx> { pub fn kind(self, tcx: TyCtxt<'tcx>) -> ty::AliasKind { match tcx.def_kind(self.def_id) { DefKind::AssocTy | DefKind::ImplTraitPlaceholder => ty::Projection, DefKind::OpaqueTy => ty::Opaque, kind => bug!("unexpected DefKind in AliasTy: {kind:?}"), } } pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { tcx.mk_alias(self.kind(tcx), self) } } /// The following methods work only with associated type projections. impl<'tcx> AliasTy<'tcx> { pub fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId { match tcx.def_kind(self.def_id) { DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.def_id), DefKind::ImplTraitPlaceholder => { tcx.parent(tcx.impl_trait_in_trait_parent(self.def_id)) } kind => bug!("expected a projection AliasTy; found {kind:?}"), } } /// Extracts the underlying trait reference and own substs from this projection. /// For example, if this is a projection of `::Item<'a>`, /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs pub fn trait_ref_and_own_substs( self, tcx: TyCtxt<'tcx>, ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) { debug_assert!(matches!(tcx.def_kind(self.def_id), DefKind::AssocTy | DefKind::AssocConst)); let trait_def_id = self.trait_def_id(tcx); let trait_generics = tcx.generics_of(trait_def_id); ( tcx.mk_trait_ref(trait_def_id, self.substs.truncate_to(tcx, trait_generics)), &self.substs[trait_generics.count()..], ) } /// Extracts the underlying trait reference from this projection. /// For example, if this is a projection of `::Item`, /// then this function would return a `T: Iterator` trait reference. /// /// WARNING: This will drop the substs for generic associated types /// consider calling [Self::trait_ref_and_own_substs] to get those /// as well. pub fn trait_ref(self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> { let def_id = self.trait_def_id(tcx); tcx.mk_trait_ref(def_id, self.substs.truncate_to(tcx, tcx.generics_of(def_id))) } pub fn self_ty(self) -> Ty<'tcx> { self.substs.type_at(0) } pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self { tcx.mk_alias_ty(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter().skip(1))) } } #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)] pub struct GenSig<'tcx> { pub resume_ty: Ty<'tcx>, pub yield_ty: Ty<'tcx>, pub return_ty: Ty<'tcx>, } pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>; /// Signature of a function type, which we have arbitrarily /// decided to use to refer to the input/output types. /// /// - `inputs`: is the list of arguments and their modes. /// - `output`: is the return type. /// - `c_variadic`: indicates whether this is a C-variadic function. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct FnSig<'tcx> { pub inputs_and_output: &'tcx List>, pub c_variadic: bool, pub unsafety: hir::Unsafety, pub abi: abi::Abi, } impl<'tcx> FnSig<'tcx> { pub fn inputs(&self) -> &'tcx [Ty<'tcx>] { &self.inputs_and_output[..self.inputs_and_output.len() - 1] } pub fn output(&self) -> Ty<'tcx> { self.inputs_and_output[self.inputs_and_output.len() - 1] } // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible // method. fn fake() -> FnSig<'tcx> { FnSig { inputs_and_output: List::empty(), c_variadic: false, unsafety: hir::Unsafety::Normal, abi: abi::Abi::Rust, } } } pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>; impl<'tcx> PolyFnSig<'tcx> { #[inline] pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> { self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs()) } #[inline] pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> { self.map_bound_ref(|fn_sig| fn_sig.inputs()[index]) } pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List>> { self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output) } #[inline] pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> { self.map_bound_ref(|fn_sig| fn_sig.output()) } pub fn c_variadic(&self) -> bool { self.skip_binder().c_variadic } pub fn unsafety(&self) -> hir::Unsafety { self.skip_binder().unsafety } pub fn abi(&self) -> abi::Abi { self.skip_binder().abi } } pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>; #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] #[derive(HashStable)] pub struct ParamTy { pub index: u32, pub name: Symbol, } impl<'tcx> ParamTy { pub fn new(index: u32, name: Symbol) -> ParamTy { ParamTy { index, name } } pub fn for_def(def: &ty::GenericParamDef) -> ParamTy { ParamTy::new(def.index, def.name) } #[inline] pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { tcx.mk_ty_param(self.index, self.name) } pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span { let generics = tcx.generics_of(item_with_generics); let type_param = generics.type_param(self, tcx); tcx.def_span(type_param.def_id) } } #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)] #[derive(HashStable)] pub struct ParamConst { pub index: u32, pub name: Symbol, } impl ParamConst { pub fn new(index: u32, name: Symbol) -> ParamConst { ParamConst { index, name } } pub fn for_def(def: &ty::GenericParamDef) -> ParamConst { ParamConst::new(def.index, def.name) } } /// Use this rather than `RegionKind`, whenever possible. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)] #[rustc_pass_by_value] pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>); impl<'tcx> Deref for Region<'tcx> { type Target = RegionKind<'tcx>; #[inline] fn deref(&self) -> &RegionKind<'tcx> { &self.0.0 } } impl<'tcx> fmt::Debug for Region<'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{:?}", self.kind()) } } #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)] #[derive(HashStable)] pub struct EarlyBoundRegion { pub def_id: DefId, pub index: u32, pub name: Symbol, } impl fmt::Debug for EarlyBoundRegion { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{}, {}", self.index, self.name) } } /// A **`const`** **v**ariable **ID**. #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] #[derive(HashStable, TyEncodable, TyDecodable)] pub struct ConstVid<'tcx> { pub index: u32, pub phantom: PhantomData<&'tcx ()>, } rustc_index::newtype_index! { /// A **region** (lifetime) **v**ariable **ID**. #[derive(HashStable)] #[debug_format = "'_#{}r"] pub struct RegionVid {} } impl Atom for RegionVid { fn index(self) -> usize { Idx::index(self) } } rustc_index::newtype_index! { #[derive(HashStable)] pub struct BoundVar {} } #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable)] pub struct BoundTy { pub var: BoundVar, pub kind: BoundTyKind, } #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable)] pub enum BoundTyKind { Anon(u32), Param(DefId, Symbol), } impl BoundTyKind { pub fn expect_anon(self) -> u32 { match self { BoundTyKind::Anon(i) => i, _ => bug!(), } } } impl From for BoundTy { fn from(var: BoundVar) -> Self { BoundTy { var, kind: BoundTyKind::Anon(var.as_u32()) } } } /// A `ProjectionPredicate` for an `ExistentialTraitRef`. #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct ExistentialProjection<'tcx> { pub def_id: DefId, pub substs: SubstsRef<'tcx>, pub term: Term<'tcx>, } pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>; impl<'tcx> ExistentialProjection<'tcx> { /// Extracts the underlying existential trait reference from this projection. /// For example, if this is a projection of `exists T. ::Item == X`, /// then this function would return an `exists T. T: Iterator` existential trait /// reference. pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> { let def_id = tcx.parent(self.def_id); let subst_count = tcx.generics_of(def_id).count() - 1; let substs = tcx.mk_substs(&self.substs[..subst_count]); ty::ExistentialTraitRef { def_id, substs } } pub fn with_self_ty( &self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>, ) -> ty::ProjectionPredicate<'tcx> { // otherwise the escaping regions would be captured by the binders debug_assert!(!self_ty.has_escaping_bound_vars()); ty::ProjectionPredicate { projection_ty: tcx .mk_alias_ty(self.def_id, [self_ty.into()].into_iter().chain(self.substs)), term: self.term, } } pub fn erase_self_ty( tcx: TyCtxt<'tcx>, projection_predicate: ty::ProjectionPredicate<'tcx>, ) -> Self { // Assert there is a Self. projection_predicate.projection_ty.substs.type_at(0); Self { def_id: projection_predicate.projection_ty.def_id, substs: tcx.mk_substs(&projection_predicate.projection_ty.substs[1..]), term: projection_predicate.term, } } } impl<'tcx> PolyExistentialProjection<'tcx> { pub fn with_self_ty( &self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>, ) -> ty::PolyProjectionPredicate<'tcx> { self.map_bound(|p| p.with_self_ty(tcx, self_ty)) } pub fn item_def_id(&self) -> DefId { self.skip_binder().def_id } } /// Region utilities impl<'tcx> Region<'tcx> { pub fn kind(self) -> RegionKind<'tcx> { *self.0.0 } pub fn get_name(self) -> Option { if self.has_name() { let name = match *self { ty::ReEarlyBound(ebr) => Some(ebr.name), ty::ReLateBound(_, br) => br.kind.get_name(), ty::ReFree(fr) => fr.bound_region.get_name(), ty::ReStatic => Some(kw::StaticLifetime), ty::RePlaceholder(placeholder) => placeholder.name.get_name(), _ => None, }; return name; } None } /// Is this region named by the user? pub fn has_name(self) -> bool { match *self { ty::ReEarlyBound(ebr) => ebr.has_name(), ty::ReLateBound(_, br) => br.kind.is_named(), ty::ReFree(fr) => fr.bound_region.is_named(), ty::ReStatic => true, ty::ReVar(..) => false, ty::RePlaceholder(placeholder) => placeholder.name.is_named(), ty::ReErased => false, ty::ReError(_) => false, } } #[inline] pub fn is_error(self) -> bool { matches!(*self, ty::ReError(_)) } #[inline] pub fn is_static(self) -> bool { matches!(*self, ty::ReStatic) } #[inline] pub fn is_erased(self) -> bool { matches!(*self, ty::ReErased) } #[inline] pub fn is_late_bound(self) -> bool { matches!(*self, ty::ReLateBound(..)) } #[inline] pub fn is_placeholder(self) -> bool { matches!(*self, ty::RePlaceholder(..)) } #[inline] pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool { match *self { ty::ReLateBound(debruijn, _) => debruijn >= index, _ => false, } } pub fn type_flags(self) -> TypeFlags { let mut flags = TypeFlags::empty(); match *self { ty::ReVar(..) => { flags = flags | TypeFlags::HAS_FREE_REGIONS; flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; flags = flags | TypeFlags::HAS_RE_INFER; } ty::RePlaceholder(..) => { flags = flags | TypeFlags::HAS_FREE_REGIONS; flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; flags = flags | TypeFlags::HAS_RE_PLACEHOLDER; } ty::ReEarlyBound(..) => { flags = flags | TypeFlags::HAS_FREE_REGIONS; flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; flags = flags | TypeFlags::HAS_RE_PARAM; } ty::ReFree { .. } => { flags = flags | TypeFlags::HAS_FREE_REGIONS; flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; } ty::ReStatic => { flags = flags | TypeFlags::HAS_FREE_REGIONS; } ty::ReLateBound(..) => { flags = flags | TypeFlags::HAS_RE_LATE_BOUND; } ty::ReErased => { flags = flags | TypeFlags::HAS_RE_ERASED; } ty::ReError(_) => {} } debug!("type_flags({:?}) = {:?}", self, flags); flags } /// Given an early-bound or free region, returns the `DefId` where it was bound. /// For example, consider the regions in this snippet of code: /// /// ```ignore (illustrative) /// impl<'a> Foo { /// // ^^ -- early bound, declared on an impl /// /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c /// // ^^ ^^ ^ anonymous, late-bound /// // | early-bound, appears in where-clauses /// // late-bound, appears only in fn args /// {..} /// } /// ``` /// /// Here, `free_region_binding_scope('a)` would return the `DefId` /// of the impl, and for all the other highlighted regions, it /// would return the `DefId` of the function. In other cases (not shown), this /// function might return the `DefId` of a closure. pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId { match *self { ty::ReEarlyBound(br) => tcx.parent(br.def_id), ty::ReFree(fr) => fr.scope, _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self), } } /// True for free regions other than `'static`. pub fn is_free(self) -> bool { matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_)) } /// True if `self` is a free region or static. pub fn is_free_or_static(self) -> bool { match *self { ty::ReStatic => true, _ => self.is_free(), } } pub fn is_var(self) -> bool { matches!(self.kind(), ty::ReVar(_)) } pub fn as_var(self) -> Option { match self.kind() { ty::ReVar(vid) => Some(vid), _ => None, } } } /// Type utilities impl<'tcx> Ty<'tcx> { #[inline(always)] pub fn kind(self) -> &'tcx TyKind<'tcx> { &self.0.0 } #[inline(always)] pub fn flags(self) -> TypeFlags { self.0.0.flags } #[inline] pub fn is_unit(self) -> bool { match self.kind() { Tuple(ref tys) => tys.is_empty(), _ => false, } } #[inline] pub fn is_never(self) -> bool { matches!(self.kind(), Never) } #[inline] pub fn is_primitive(self) -> bool { self.kind().is_primitive() } #[inline] pub fn is_adt(self) -> bool { matches!(self.kind(), Adt(..)) } #[inline] pub fn is_ref(self) -> bool { matches!(self.kind(), Ref(..)) } #[inline] pub fn is_ty_var(self) -> bool { matches!(self.kind(), Infer(TyVar(_))) } #[inline] pub fn ty_vid(self) -> Option { match self.kind() { &Infer(TyVar(vid)) => Some(vid), _ => None, } } #[inline] pub fn is_ty_or_numeric_infer(self) -> bool { matches!(self.kind(), Infer(_)) } #[inline] pub fn is_phantom_data(self) -> bool { if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false } } #[inline] pub fn is_bool(self) -> bool { *self.kind() == Bool } /// Returns `true` if this type is a `str`. #[inline] pub fn is_str(self) -> bool { *self.kind() == Str } #[inline] pub fn is_param(self, index: u32) -> bool { match self.kind() { ty::Param(ref data) => data.index == index, _ => false, } } #[inline] pub fn is_slice(self) -> bool { matches!(self.kind(), Slice(_)) } #[inline] pub fn is_array_slice(self) -> bool { match self.kind() { Slice(_) => true, RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)), _ => false, } } #[inline] pub fn is_array(self) -> bool { matches!(self.kind(), Array(..)) } #[inline] pub fn is_simd(self) -> bool { match self.kind() { Adt(def, _) => def.repr().simd(), _ => false, } } pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { match self.kind() { Array(ty, _) | Slice(ty) => *ty, Str => tcx.types.u8, _ => bug!("`sequence_element_type` called on non-sequence value: {}", self), } } pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) { match self.kind() { Adt(def, substs) => { assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type"); let variant = def.non_enum_variant(); let f0_ty = variant.fields[0].ty(tcx, substs); match f0_ty.kind() { // If the first field is an array, we assume it is the only field and its // elements are the SIMD components. Array(f0_elem_ty, f0_len) => { // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112 // The way we evaluate the `N` in `[T; N]` here only works since we use // `simd_size_and_type` post-monomorphization. It will probably start to ICE // if we use it in generic code. See the `simd-array-trait` ui test. (f0_len.eval_target_usize(tcx, ParamEnv::empty()) as u64, *f0_elem_ty) } // Otherwise, the fields of this Adt are the SIMD components (and we assume they // all have the same type). _ => (variant.fields.len() as u64, f0_ty), } } _ => bug!("`simd_size_and_type` called on invalid type"), } } #[inline] pub fn is_region_ptr(self) -> bool { matches!(self.kind(), Ref(..)) } #[inline] pub fn is_mutable_ptr(self) -> bool { matches!( self.kind(), RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. }) | Ref(_, _, hir::Mutability::Mut) ) } /// Get the mutability of the reference or `None` when not a reference #[inline] pub fn ref_mutability(self) -> Option { match self.kind() { Ref(_, _, mutability) => Some(*mutability), _ => None, } } #[inline] pub fn is_unsafe_ptr(self) -> bool { matches!(self.kind(), RawPtr(_)) } /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer). #[inline] pub fn is_any_ptr(self) -> bool { self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr() } #[inline] pub fn is_box(self) -> bool { match self.kind() { Adt(def, _) => def.is_box(), _ => false, } } /// Panics if called on any type other than `Box`. pub fn boxed_ty(self) -> Ty<'tcx> { match self.kind() { Adt(def, substs) if def.is_box() => substs.type_at(0), _ => bug!("`boxed_ty` is called on non-box type {:?}", self), } } /// A scalar type is one that denotes an atomic datum, with no sub-components. /// (A RawPtr is scalar because it represents a non-managed pointer, so its /// contents are abstract to rustc.) #[inline] pub fn is_scalar(self) -> bool { matches!( self.kind(), Bool | Char | Int(_) | Float(_) | Uint(_) | FnDef(..) | FnPtr(_) | RawPtr(_) | Infer(IntVar(_) | FloatVar(_)) ) } /// Returns `true` if this type is a floating point type. #[inline] pub fn is_floating_point(self) -> bool { matches!(self.kind(), Float(_) | Infer(FloatVar(_))) } #[inline] pub fn is_trait(self) -> bool { matches!(self.kind(), Dynamic(_, _, ty::Dyn)) } #[inline] pub fn is_dyn_star(self) -> bool { matches!(self.kind(), Dynamic(_, _, ty::DynStar)) } #[inline] pub fn is_enum(self) -> bool { matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum()) } #[inline] pub fn is_union(self) -> bool { matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union()) } #[inline] pub fn is_closure(self) -> bool { matches!(self.kind(), Closure(..)) } #[inline] pub fn is_generator(self) -> bool { matches!(self.kind(), Generator(..)) } #[inline] pub fn is_integral(self) -> bool { matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_)) } #[inline] pub fn is_fresh_ty(self) -> bool { matches!(self.kind(), Infer(FreshTy(_))) } #[inline] pub fn is_fresh(self) -> bool { matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_))) } #[inline] pub fn is_char(self) -> bool { matches!(self.kind(), Char) } #[inline] pub fn is_numeric(self) -> bool { self.is_integral() || self.is_floating_point() } #[inline] pub fn is_signed(self) -> bool { matches!(self.kind(), Int(_)) } #[inline] pub fn is_ptr_sized_integral(self) -> bool { matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize)) } #[inline] pub fn has_concrete_skeleton(self) -> bool { !matches!(self.kind(), Param(_) | Infer(_) | Error(_)) } /// Checks whether a type recursively contains another type /// /// Example: `Option<()>` contains `()` pub fn contains(self, other: Ty<'tcx>) -> bool { struct ContainsTyVisitor<'tcx>(Ty<'tcx>); impl<'tcx> TypeVisitor> for ContainsTyVisitor<'tcx> { type BreakTy = (); fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow { if self.0 == t { ControlFlow::Break(()) } else { t.super_visit_with(self) } } } let cf = self.visit_with(&mut ContainsTyVisitor(other)); cf.is_break() } /// Checks whether a type recursively contains any closure /// /// Example: `Option<[closure@file.rs:4:20]>` returns true pub fn contains_closure(self) -> bool { struct ContainsClosureVisitor; impl<'tcx> TypeVisitor> for ContainsClosureVisitor { type BreakTy = (); fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow { if let ty::Closure(_, _) = t.kind() { ControlFlow::Break(()) } else { t.super_visit_with(self) } } } let cf = self.visit_with(&mut ContainsClosureVisitor); cf.is_break() } /// Returns the type and mutability of `*ty`. /// /// The parameter `explicit` indicates if this is an *explicit* dereference. /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly. pub fn builtin_deref(self, explicit: bool) -> Option> { match self.kind() { Adt(def, _) if def.is_box() => { Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not }) } Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }), RawPtr(mt) if explicit => Some(*mt), _ => None, } } /// Returns the type of `ty[i]`. pub fn builtin_index(self) -> Option> { match self.kind() { Array(ty, _) | Slice(ty) => Some(*ty), _ => None, } } pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> { match self.kind() { FnDef(def_id, substs) => tcx.fn_sig(*def_id).subst(tcx, substs), FnPtr(f) => *f, Error(_) => { // ignore errors (#54954) ty::Binder::dummy(FnSig::fake()) } Closure(..) => bug!( "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`", ), _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self), } } #[inline] pub fn is_fn(self) -> bool { matches!(self.kind(), FnDef(..) | FnPtr(_)) } #[inline] pub fn is_fn_ptr(self) -> bool { matches!(self.kind(), FnPtr(_)) } #[inline] pub fn is_impl_trait(self) -> bool { matches!(self.kind(), Alias(ty::Opaque, ..)) } #[inline] pub fn ty_adt_def(self) -> Option> { match self.kind() { Adt(adt, _) => Some(*adt), _ => None, } } /// Iterates over tuple fields. /// Panics when called on anything but a tuple. #[inline] pub fn tuple_fields(self) -> &'tcx List> { match self.kind() { Tuple(substs) => substs, _ => bug!("tuple_fields called on non-tuple"), } } /// If the type contains variants, returns the valid range of variant indices. // // FIXME: This requires the optimized MIR in the case of generators. #[inline] pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option> { match self.kind() { TyKind::Adt(adt, _) => Some(adt.variant_range()), TyKind::Generator(def_id, substs, _) => { Some(substs.as_generator().variant_range(*def_id, tcx)) } _ => None, } } /// If the type contains variants, returns the variant for `variant_index`. /// Panics if `variant_index` is out of range. // // FIXME: This requires the optimized MIR in the case of generators. #[inline] pub fn discriminant_for_variant( self, tcx: TyCtxt<'tcx>, variant_index: VariantIdx, ) -> Option> { match self.kind() { TyKind::Adt(adt, _) if adt.variants().is_empty() => { // This can actually happen during CTFE, see // https://github.com/rust-lang/rust/issues/89765. None } TyKind::Adt(adt, _) if adt.is_enum() => { Some(adt.discriminant_for_variant(tcx, variant_index)) } TyKind::Generator(def_id, substs, _) => { Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index)) } _ => None, } } /// Returns the type of the discriminant of this type. pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { match self.kind() { ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx), ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx), ty::Param(_) | ty::Alias(..) | ty::Infer(ty::TyVar(_)) => { let assoc_items = tcx.associated_item_def_ids( tcx.require_lang_item(hir::LangItem::DiscriminantKind, None), ); tcx.mk_projection(assoc_items[0], tcx.mk_substs(&[self.into()])) } ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Adt(..) | ty::Foreign(_) | ty::Str | ty::Array(..) | ty::Slice(_) | ty::RawPtr(_) | ty::Ref(..) | ty::FnDef(..) | ty::FnPtr(..) | ty::Dynamic(..) | ty::Closure(..) | ty::GeneratorWitness(..) | ty::GeneratorWitnessMIR(..) | ty::Never | ty::Tuple(_) | ty::Error(_) | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8, ty::Bound(..) | ty::Placeholder(_) | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => { bug!("`discriminant_ty` applied to unexpected type: {:?}", self) } } } /// Returns the type of metadata for (potentially fat) pointers to this type, /// and a boolean signifying if this is conditional on this type being `Sized`. pub fn ptr_metadata_ty( self, tcx: TyCtxt<'tcx>, normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>, ) -> (Ty<'tcx>, bool) { let tail = tcx.struct_tail_with_normalize(self, normalize, || {}); match tail.kind() { // Sized types ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) | ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) | ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) | ty::Char | ty::Ref(..) | ty::Generator(..) | ty::GeneratorWitness(..) | ty::GeneratorWitnessMIR(..) | ty::Array(..) | ty::Closure(..) | ty::Never | ty::Error(_) // Extern types have metadata = (). | ty::Foreign(..) // If returned by `struct_tail_without_normalization` this is a unit struct // without any fields, or not a struct, and therefore is Sized. | ty::Adt(..) // If returned by `struct_tail_without_normalization` this is the empty tuple, // a.k.a. unit type, which is Sized | ty::Tuple(..) => (tcx.types.unit, false), ty::Str | ty::Slice(_) => (tcx.types.usize, false), ty::Dynamic(..) => { let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, None); (tcx.type_of(dyn_metadata).subst(tcx, &[tail.into()]), false) }, // type parameters only have unit metadata if they're sized, so return true // to make sure we double check this during confirmation ty::Param(_) | ty::Alias(..) => (tcx.types.unit, true), ty::Infer(ty::TyVar(_)) | ty::Bound(..) | ty::Placeholder(..) | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => { bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail) } } } /// When we create a closure, we record its kind (i.e., what trait /// it implements) into its `ClosureSubsts` using a type /// parameter. This is kind of a phantom type, except that the /// most convenient thing for us to are the integral types. This /// function converts such a special type into the closure /// kind. To go the other way, use `closure_kind.to_ty(tcx)`. /// /// Note that during type checking, we use an inference variable /// to represent the closure kind, because it has not yet been /// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`) /// is complete, that type variable will be unified. pub fn to_opt_closure_kind(self) -> Option { match self.kind() { Int(int_ty) => match int_ty { ty::IntTy::I8 => Some(ty::ClosureKind::Fn), ty::IntTy::I16 => Some(ty::ClosureKind::FnMut), ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce), _ => bug!("cannot convert type `{:?}` to a closure kind", self), }, // "Bound" types appear in canonical queries when the // closure type is not yet known Bound(..) | Infer(_) => None, Error(_) => Some(ty::ClosureKind::Fn), _ => bug!("cannot convert type `{:?}` to a closure kind", self), } } /// Fast path helper for testing if a type is `Sized`. /// /// Returning true means the type is known to be sized. Returning /// `false` means nothing -- could be sized, might not be. /// /// Note that we could never rely on the fact that a type such as `[_]` is /// trivially `!Sized` because we could be in a type environment with a /// bound such as `[_]: Copy`. A function with such a bound obviously never /// can be called, but that doesn't mean it shouldn't typecheck. This is why /// this method doesn't return `Option`. pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool { match self.kind() { ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) | ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) | ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) | ty::Char | ty::Ref(..) | ty::Generator(..) | ty::GeneratorWitness(..) | ty::GeneratorWitnessMIR(..) | ty::Array(..) | ty::Closure(..) | ty::Never | ty::Error(_) => true, ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false, ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)), ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(), ty::Alias(..) | ty::Param(_) => false, ty::Infer(ty::TyVar(_)) => false, ty::Bound(..) | ty::Placeholder(..) | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => { bug!("`is_trivially_sized` applied to unexpected type: {:?}", self) } } } /// Fast path helper for primitives which are always `Copy` and which /// have a side-effect-free `Clone` impl. /// /// Returning true means the type is known to be pure and `Copy+Clone`. /// Returning `false` means nothing -- could be `Copy`, might not be. /// /// This is mostly useful for optimizations, as there are the types /// on which we can replace cloning with dereferencing. pub fn is_trivially_pure_clone_copy(self) -> bool { match self.kind() { ty::Bool | ty::Char | ty::Never => true, // These aren't even `Clone` ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false, ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_)) | ty::Int(..) | ty::Uint(..) | ty::Float(..) => true, // The voldemort ZSTs are fine. ty::FnDef(..) => true, ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(), // A 100-tuple isn't "trivial", so doing this only for reasonable sizes. ty::Tuple(field_tys) => { field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy) } // Sometimes traits aren't implemented for every ABI or arity, // because we can't be generic over everything yet. ty::FnPtr(..) => false, // Definitely absolutely not copy. ty::Ref(_, _, hir::Mutability::Mut) => false, // Thin pointers & thin shared references are pure-clone-copy, but for // anything with custom metadata it might be more complicated. ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false, ty::Generator(..) | ty::GeneratorWitness(..) | ty::GeneratorWitnessMIR(..) => false, // Might be, but not "trivial" so just giving the safe answer. ty::Adt(..) | ty::Closure(..) => false, // Needs normalization or revealing to determine, so no is the safe answer. ty::Alias(..) => false, ty::Param(..) | ty::Infer(..) | ty::Error(..) => false, ty::Bound(..) | ty::Placeholder(..) => { bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self); } } } /// If `self` is a primitive, return its [`Symbol`]. pub fn primitive_symbol(self) -> Option { match self.kind() { ty::Bool => Some(sym::bool), ty::Char => Some(sym::char), ty::Float(f) => match f { ty::FloatTy::F32 => Some(sym::f32), ty::FloatTy::F64 => Some(sym::f64), }, ty::Int(f) => match f { ty::IntTy::Isize => Some(sym::isize), ty::IntTy::I8 => Some(sym::i8), ty::IntTy::I16 => Some(sym::i16), ty::IntTy::I32 => Some(sym::i32), ty::IntTy::I64 => Some(sym::i64), ty::IntTy::I128 => Some(sym::i128), }, ty::Uint(f) => match f { ty::UintTy::Usize => Some(sym::usize), ty::UintTy::U8 => Some(sym::u8), ty::UintTy::U16 => Some(sym::u16), ty::UintTy::U32 => Some(sym::u32), ty::UintTy::U64 => Some(sym::u64), ty::UintTy::U128 => Some(sym::u128), }, _ => None, } } } /// Extra information about why we ended up with a particular variance. /// This is only used to add more information to error messages, and /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo` /// may lead to confusing notes in error messages, it will never cause /// a miscompilation or unsoundness. /// /// When in doubt, use `VarianceDiagInfo::default()` #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)] pub enum VarianceDiagInfo<'tcx> { /// No additional information - this is the default. /// We will not add any additional information to error messages. #[default] None, /// We switched our variance because a generic argument occurs inside /// the invariant generic argument of another type. Invariant { /// The generic type containing the generic parameter /// that changes the variance (e.g. `*mut T`, `MyStruct`) ty: Ty<'tcx>, /// The index of the generic parameter being used /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`) param_index: u32, }, } impl<'tcx> VarianceDiagInfo<'tcx> { /// Mirrors `Variance::xform` - used to 'combine' the existing /// and new `VarianceDiagInfo`s when our variance changes. pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> { // For now, just use the first `VarianceDiagInfo::Invariant` that we see match self { VarianceDiagInfo::None => other, VarianceDiagInfo::Invariant { .. } => self, } } }