//! This module contains `TyKind` and its major components. #![allow(rustc::usage_of_ty_tykind)] use self::TyKind::*; use crate::infer::canonical::Canonical; use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef}; use crate::ty::InferTy::{self, *}; use crate::ty::{ self, AdtDef, DefIdTree, Discr, Ty, TyCtxt, TypeFlags, TypeFoldable, WithConstness, }; use crate::ty::{DelaySpanBugEmitted, List, ParamEnv, TyS}; use polonius_engine::Atom; use rustc_data_structures::captures::Captures; use rustc_hir as hir; use rustc_hir::def_id::DefId; use rustc_index::vec::Idx; use rustc_macros::HashStable; use rustc_span::symbol::{kw, Symbol}; use rustc_target::abi::VariantIdx; use rustc_target::spec::abi; use std::borrow::Cow; use std::cmp::Ordering; use std::marker::PhantomData; use std::ops::Range; use ty::util::IntTypeExt; #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, 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), /// 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 kind: BoundRegionKind, } impl BoundRegion { /// When canonicalizing, we replace unbound inference variables and free /// regions with anonymous late bound regions. This method asserts that /// we have an anonymous late bound region, which hence may refer to /// a canonical variable. pub fn assert_bound_var(&self) -> BoundVar { match self.kind { BoundRegionKind::BrAnon(var) => BoundVar::from_u32(var), _ => bug!("bound region is not anonymous"), } } } impl BoundRegionKind { pub fn is_named(&self) -> bool { match *self { BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime, _ => false, } } } /// Defines the kinds of types. /// /// N.B., if you change this, you'll probably want to change the corresponding /// AST structure in `librustc_ast/ast.rs` as well. #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)] #[derive(HashStable)] #[rustc_diagnostic_item = "TyKind"] pub enum TyKind<'tcx> { /// The primitive boolean type. Written as `bool`. Bool, /// The primitive character type; holds a Unicode scalar value /// (a non-surrogate code point). Written as `char`. Char, /// A primitive signed integer type. For example, `i32`. Int(ty::IntTy), /// A primitive unsigned integer type. For example, `u32`. Uint(ty::UintTy), /// A primitive floating-point type. For example, `f64`. Float(ty::FloatTy), /// Algebraic data types (ADT). For example: structures, enumerations and unions. /// /// InternalSubsts here, possibly against intuition, *may* contain `Param`s. /// That is, even after substitution it is possible that there are type /// variables. This happens when the `Adt` corresponds to an ADT /// definition and not a concrete use of it. Adt(&'tcx AdtDef, SubstsRef<'tcx>), /// An unsized FFI type that is opaque to Rust. Written as `extern type T`. Foreign(DefId), /// The pointee of a string slice. Written as `str`. Str, /// An array with the given length. Written as `[T; n]`. Array(Ty<'tcx>, &'tcx ty::Const<'tcx>), /// The pointee of an array slice. Written as `[T]`. Slice(Ty<'tcx>), /// A raw pointer. Written as `*mut T` or `*const T` RawPtr(TypeAndMut<'tcx>), /// A reference; a pointer with an associated lifetime. Written as /// `&'a mut T` or `&'a T`. Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability), /// The anonymous type of a function declaration/definition. Each /// function has a unique type, which is output (for a function /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`. /// /// For example the type of `bar` here: /// /// ```rust /// fn foo() -> i32 { 1 } /// let bar = foo; // bar: fn() -> i32 {foo} /// ``` FnDef(DefId, SubstsRef<'tcx>), /// A pointer to a function. Written as `fn() -> i32`. /// /// For example the type of `bar` here: /// /// ```rust /// fn foo() -> i32 { 1 } /// let bar: fn() -> i32 = foo; /// ``` FnPtr(PolyFnSig<'tcx>), /// A trait object. Written as `dyn for<'b> Trait<'b, Assoc = u32> + Send + 'a`. Dynamic(&'tcx List>>, ty::Region<'tcx>), /// The anonymous type of a closure. Used to represent the type of /// `|a| a`. Closure(DefId, SubstsRef<'tcx>), /// The anonymous type of a generator. Used to represent the type of /// `|a| yield a`. Generator(DefId, SubstsRef<'tcx>, hir::Movability), /// A type representing the types stored inside a generator. /// This should only appear in GeneratorInteriors. GeneratorWitness(Binder<&'tcx List>>), /// The never type `!`. Never, /// A tuple type. For example, `(i32, bool)`. /// Use `TyS::tuple_fields` to iterate over the field types. Tuple(SubstsRef<'tcx>), /// The projection of an associated type. For example, /// `>::N`. Projection(ProjectionTy<'tcx>), /// Opaque (`impl Trait`) type found in a return type. /// The `DefId` comes either from /// * the `impl Trait` ast::Ty node, /// * or the `type Foo = impl Trait` declaration /// The substitutions are for the generics of the function in question. /// After typeck, the concrete type can be found in the `types` map. Opaque(DefId, SubstsRef<'tcx>), /// A type parameter; for example, `T` in `fn f(x: T) {}`. Param(ParamTy), /// Bound type variable, used only when preparing a trait query. Bound(ty::DebruijnIndex, BoundTy), /// A placeholder type - universally quantified higher-ranked type. Placeholder(ty::PlaceholderType), /// A type variable used during type checking. Infer(InferTy), /// A placeholder for a type which could not be computed; this is /// propagated to avoid useless error messages. Error(DelaySpanBugEmitted), } impl TyKind<'tcx> { #[inline] pub fn is_primitive(&self) -> bool { matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_)) } /// Get the article ("a" or "an") to use with this type. pub 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<'_>, 24); /// A closure can be modeled as a struct that looks like: /// /// 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 /// `TyS::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 an 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: /// /// fn foo<'a, T>(data: &'a mut T) { /// do(|| data.count += 1) /// } /// /// the type of the closure would be something like: /// /// 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: /// /// 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, Debug, TypeFoldable)] 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( 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_typeck::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()), } } } /// Similar to `ClosureSubsts`; see the above documentation for more. #[derive(Copy, Clone, Debug, TypeFoldable)] 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( 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| layout.field_tys[*field].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)] 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(), } } } #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] 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.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)) } (AutoTrait(ref a), AutoTrait(ref b)) => { tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash) } (Trait(_), _) => Ordering::Less, (Projection(_), Trait(_)) => Ordering::Greater, (Projection(_), _) => Ordering::Less, (AutoTrait(_), _) => Ordering::Greater, } } } impl<'tcx> Binder> { 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 trait_ref = self.rebind(ty::TraitRef { def_id: did, substs: tcx.mk_substs_trait(self_ty, &[]), }); 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 + '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: /// /// 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, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct TraitRef<'tcx> { pub def_id: DefId, pub substs: SubstsRef<'tcx>, } impl<'tcx> TraitRef<'tcx> { pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> { TraitRef { def_id, substs } } /// 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) -> TraitRef<'tcx> { TraitRef { def_id, substs: 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); ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) } } } pub type PolyTraitRef<'tcx> = Binder>; impl<'tcx> PolyTraitRef<'tcx> { pub fn self_ty(&self) -> Binder> { self.map_bound_ref(|tr| tr.self_ty()) } pub fn def_id(&self) -> DefId { self.skip_binder().def_id } pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> { self.map_bound(|trait_ref| ty::TraitPredicate { trait_ref }) } } /// An existential reference to a trait, where `Self` is erased. /// For example, the trait object `Trait<'a, 'b, X, Y>` is: /// /// 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)] 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.intern_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()); ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) } } } pub type PolyExistentialTraitRef<'tcx> = Binder>; 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)) } } /// 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`). Note that when we instantiate, /// erase, or otherwise "discharge" these bound vars, we change the /// type from `Binder` 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)] pub struct Binder(T); impl Binder { /// 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. pub fn dummy<'tcx>(value: T) -> Binder where T: TypeFoldable<'tcx>, { debug_assert!(!value.has_escaping_bound_vars()); Binder(value) } /// Wraps `value` in a binder, binding higher-ranked vars (if any). pub fn bind(value: T) -> Binder { Binder(value) } /// Wraps `value` in a binder without actually binding any currently /// unbound variables. /// /// Note that this will shift all debrujin indices of escaping bound variables /// by 1 to avoid accidential captures. pub fn wrap_nonbinding(tcx: TyCtxt<'tcx>, value: T) -> Binder where T: TypeFoldable<'tcx>, { if value.has_escaping_bound_vars() { Binder::bind(super::fold::shift_vars(tcx, value, 1)) } else { Binder::dummy(value) } } /// 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 as_ref(&self) -> Binder<&T> { Binder(&self.0) } pub fn map_bound_ref(&self, f: F) -> Binder where F: FnOnce(&T) -> U, { self.as_ref().map_bound(f) } pub fn map_bound(self, f: F) -> Binder where F: FnOnce(T) -> U, { Binder(f(self.0)) } /// 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 { Binder(value) } /// 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<'tcx>(self) -> Option where T: TypeFoldable<'tcx>, { if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) } } /// Given two things that have the same binder level, /// and an operation that wraps on their contents, executes the operation /// and then wraps its result. /// /// `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 value. pub fn fuse(self, u: Binder, f: F) -> Binder where F: FnOnce(T, U) -> R, { Binder(f(self.0, u.0)) } /// 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, Binder) where F: FnOnce(T) -> (U, V), { let (u, v) = f(self.0); (Binder(u), Binder(v)) } } impl Binder> { pub fn transpose(self) -> Option> { self.0.map(Binder) } } /// Represents the projection of an associated type. In explicit UFCS /// form this would be written `>::N`. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct ProjectionTy<'tcx> { /// The parameters of the associated item. pub substs: SubstsRef<'tcx>, /// The `DefId` of the `TraitItem` for the associated type `N`. /// /// Note that this is not the `DefId` of the `TraitRef` containing this /// associated type, which is in `tcx.associated_item(item_def_id).container`. pub item_def_id: DefId, } impl<'tcx> ProjectionTy<'tcx> { pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId { tcx.associated_item(self.item_def_id).container.id() } /// 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>]) { let def_id = tcx.associated_item(self.item_def_id).container.id(); let trait_generics = tcx.generics_of(def_id); ( ty::TraitRef { def_id, substs: 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); ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) } } pub fn self_ty(&self) -> Ty<'tcx> { self.substs.type_at(0) } } #[derive(Copy, Clone, Debug, TypeFoldable)] pub struct GenSig<'tcx> { pub resume_ty: Ty<'tcx>, pub yield_ty: Ty<'tcx>, pub return_ty: Ty<'tcx>, } pub type PolyGenSig<'tcx> = Binder>; impl<'tcx> PolyGenSig<'tcx> { pub fn resume_ty(&self) -> ty::Binder> { self.map_bound_ref(|sig| sig.resume_ty) } pub fn yield_ty(&self) -> ty::Binder> { self.map_bound_ref(|sig| sig.yield_ty) } pub fn return_ty(&self) -> ty::Binder> { self.map_bound_ref(|sig| sig.return_ty) } } /// 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)] 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>; impl<'tcx> PolyFnSig<'tcx> { #[inline] pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> { self.map_bound_ref(|fn_sig| fn_sig.inputs()) } #[inline] pub fn input(&self, index: usize) -> ty::Binder> { self.map_bound_ref(|fn_sig| fn_sig.inputs()[index]) } pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List>> { self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output) } #[inline] pub fn output(&self) -> ty::Binder> { 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>>; #[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_self() -> ParamTy { ParamTy::new(0, kw::SelfUpper) } 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) } } #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)] #[derive(HashStable)] pub struct ParamConst { pub index: u32, pub name: Symbol, } impl<'tcx> 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) } pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx ty::Const<'tcx> { tcx.mk_const_param(self.index, self.name, ty) } } pub type Region<'tcx> = &'tcx RegionKind; /// Representation of regions. Note that the NLL checker uses a distinct /// representation of regions. For this reason, it internally replaces all the /// regions with inference variables -- the index of the variable is then used /// to index into internal NLL data structures. See `rustc_mir::borrow_check` /// module for more information. /// /// ## The Region lattice within a given function /// /// In general, the region lattice looks like /// /// ``` /// static ----------+-----...------+ (greatest) /// | | | /// early-bound and | | /// free regions | | /// | | | /// | | | /// empty(root) placeholder(U1) | /// | / | /// | / placeholder(Un) /// empty(U1) -- / /// | / /// ... / /// | / /// empty(Un) -------- (smallest) /// ``` /// /// Early-bound/free regions are the named lifetimes in scope from the /// function declaration. They have relationships to one another /// determined based on the declared relationships from the /// function. /// /// Note that inference variables and bound regions are not included /// in this diagram. In the case of inference variables, they should /// be inferred to some other region from the diagram. In the case of /// bound regions, they are excluded because they don't make sense to /// include -- the diagram indicates the relationship between free /// regions. /// /// ## Inference variables /// /// During region inference, we sometimes create inference variables, /// represented as `ReVar`. These will be inferred by the code in /// `infer::lexical_region_resolve` to some free region from the /// lattice above (the minimal region that meets the /// constraints). /// /// During NLL checking, where regions are defined differently, we /// also use `ReVar` -- in that case, the index is used to index into /// the NLL region checker's data structures. The variable may in fact /// represent either a free region or an inference variable, in that /// case. /// /// ## Bound Regions /// /// These are regions that are stored behind a binder and must be substituted /// with some concrete region before being used. There are two kind of /// bound regions: early-bound, which are bound in an item's `Generics`, /// and are substituted by a `InternalSubsts`, and late-bound, which are part of /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by /// the likes of `liberate_late_bound_regions`. The distinction exists /// because higher-ranked lifetimes aren't supported in all places. See [1][2]. /// /// Unlike `Param`s, bound regions are not supposed to exist "in the wild" /// outside their binder, e.g., in types passed to type inference, and /// should first be substituted (by placeholder regions, free regions, /// or region variables). /// /// ## Placeholder and Free Regions /// /// One often wants to work with bound regions without knowing their precise /// identity. For example, when checking a function, the lifetime of a borrow /// can end up being assigned to some region parameter. In these cases, /// it must be ensured that bounds on the region can't be accidentally /// assumed without being checked. /// /// To do this, we replace the bound regions with placeholder markers, /// which don't satisfy any relation not explicitly provided. /// /// There are two kinds of placeholder regions in rustc: `ReFree` and /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed /// to be used. These also support explicit bounds: both the internally-stored /// *scope*, which the region is assumed to outlive, as well as other /// relations stored in the `FreeRegionMap`. Note that these relations /// aren't checked when you `make_subregion` (or `eq_types`), only by /// `resolve_regions_and_report_errors`. /// /// When working with higher-ranked types, some region relations aren't /// yet known, so you can't just call `resolve_regions_and_report_errors`. /// `RePlaceholder` is designed for this purpose. In these contexts, /// there's also the risk that some inference variable laying around will /// get unified with your placeholder region: if you want to check whether /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a` /// with a placeholder region `'%a`, the variable `'_` would just be /// instantiated to the placeholder region `'%a`, which is wrong because /// the inference variable is supposed to satisfy the relation /// *for every value of the placeholder region*. To ensure that doesn't /// happen, you can use `leak_check`. This is more clearly explained /// by the [rustc dev guide]. /// /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/ /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/ /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html #[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)] pub enum RegionKind { /// Region bound in a type or fn declaration which will be /// substituted 'early' -- that is, at the same time when type /// parameters are substituted. ReEarlyBound(EarlyBoundRegion), /// Region bound in a function scope, which will be substituted when the /// function is called. ReLateBound(ty::DebruijnIndex, BoundRegion), /// When checking a function body, the types of all arguments and so forth /// that refer to bound region parameters are modified to refer to free /// region parameters. ReFree(FreeRegion), /// Static data that has an "infinite" lifetime. Top in the region lattice. ReStatic, /// A region variable. Should not exist after typeck. ReVar(RegionVid), /// A placeholder region -- basically, the higher-ranked version of `ReFree`. /// Should not exist after typeck. RePlaceholder(ty::PlaceholderRegion), /// Empty lifetime is for data that is never accessed. We tag the /// empty lifetime with a universe -- the idea is that we don't /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable. /// Therefore, the `'empty` in a universe `U` is less than all /// regions visible from `U`, but not less than regions not visible /// from `U`. ReEmpty(ty::UniverseIndex), /// Erased region, used by trait selection, in MIR and during codegen. ReErased, } #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)] pub struct EarlyBoundRegion { pub def_id: DefId, pub index: u32, pub name: Symbol, } /// A **`const`** **v**ariable **ID**. #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)] pub struct ConstVid<'tcx> { pub index: u32, pub phantom: PhantomData<&'tcx ()>, } rustc_index::newtype_index! { /// A **region** (lifetime) **v**ariable **ID**. pub struct RegionVid { DEBUG_FORMAT = custom, } } impl Atom for RegionVid { fn index(self) -> usize { Idx::index(self) } } rustc_index::newtype_index! { 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, Param(Symbol), } impl From for BoundTy { fn from(var: BoundVar) -> Self { BoundTy { var, kind: BoundTyKind::Anon } } } /// A `ProjectionPredicate` for an `ExistentialTraitRef`. #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct ExistentialProjection<'tcx> { pub item_def_id: DefId, pub substs: SubstsRef<'tcx>, pub ty: Ty<'tcx>, } pub type PolyExistentialProjection<'tcx> = Binder>; 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 a `exists T. T: Iterator` existential trait /// reference. pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> { let def_id = tcx.associated_item(self.item_def_id).container.id(); let subst_count = tcx.generics_of(def_id).count() - 1; let substs = tcx.intern_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: ty::ProjectionTy { item_def_id: self.item_def_id, substs: tcx.mk_substs_trait(self_ty, self.substs), }, ty: self.ty, } } 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 { item_def_id: projection_predicate.projection_ty.item_def_id, substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]), ty: projection_predicate.ty, } } } 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().item_def_id } } /// Region utilities impl RegionKind { /// Is this region named by the user? pub fn has_name(&self) -> bool { match *self { RegionKind::ReEarlyBound(ebr) => ebr.has_name(), RegionKind::ReLateBound(_, br) => br.kind.is_named(), RegionKind::ReFree(fr) => fr.bound_region.is_named(), RegionKind::ReStatic => true, RegionKind::ReVar(..) => false, RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(), RegionKind::ReEmpty(_) => false, RegionKind::ReErased => false, } } #[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, } } /// Adjusts any De Bruijn indices so as to make `to_binder` the /// innermost binder. That is, if we have something bound at `to_binder`, /// it will now be bound at INNERMOST. This is an appropriate thing to do /// when moving a region out from inside binders: /// /// ``` /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _) /// // Binder: D3 D2 D1 ^^ /// ``` /// /// Here, the region `'a` would have the De Bruijn index D3, /// because it is the bound 3 binders out. However, if we wanted /// to refer to that region `'a` in the second argument (the `_`), /// those two binders would not be in scope. In that case, we /// might invoke `shift_out_to_binder(D3)`. This would adjust the /// De Bruijn index of `'a` to D1 (the innermost binder). /// /// If we invoke `shift_out_to_binder` and the region is in fact /// bound by one of the binders we are shifting out of, that is an /// error (and should fail an assertion failure). pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind { match *self { ty::ReLateBound(debruijn, r) => { ty::ReLateBound(debruijn.shifted_out_to_binder(to_binder), r) } r => r, } } 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::ReEmpty(_) | 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; } } 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: /// /// ``` /// 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).unwrap(), ty::ReFree(fr) => fr.scope, _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self), } } } /// Type utilities impl<'tcx> TyS<'tcx> { #[inline(always)] pub fn kind(&self) -> &TyKind<'tcx> { &self.kind } #[inline(always)] pub fn flags(&self) -> TypeFlags { self.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 is_ty_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 { match self.kind() { RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_) | Str), _ => 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.mk_mach_uint(ty::UintTy::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) => { let variant = def.non_enum_variant(); let f0_ty = variant.fields[0].ty(tcx, substs); match f0_ty.kind() { 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_usize(tcx, ParamEnv::empty()) as u64, f0_elem_ty) } _ => (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(..)) } #[inline] pub fn is_enum(&self) -> bool { match self.kind() { Adt(adt_def, _) => adt_def.is_enum(), _ => false, } } #[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 is_machine(&self) -> bool { matches!(self.kind(), Int(..) | Uint(..) | Float(..)) } #[inline] pub fn has_concrete_skeleton(&self) -> bool { !matches!(self.kind(), Param(_) | Infer(_) | Error(_)) } /// 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, 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(), Opaque(..)) } #[inline] pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> { match self.kind() { Adt(adt, _) => Some(adt), _ => None, } } /// Iterates over tuple fields. /// Panics when called on anything but a tuple. pub fn tuple_fields(&self) -> impl DoubleEndedIterator> { match self.kind() { Tuple(substs) => substs.iter().map(|field| field.expect_ty()), _ => bug!("tuple_fields called on non-tuple"), } } /// Get the `i`-th element of a tuple. /// Panics when called on anything but a tuple. pub fn tuple_element_ty(&self, i: usize) -> Option> { match self.kind() { Tuple(substs) => substs.iter().nth(i).map(|field| field.expect_ty()), _ => 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() => { bug!("discriminant_for_variant called on zero variant enum"); } 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(&'tcx 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::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => { let assoc_items = tcx.associated_items(tcx.lang_items().discriminant_kind_trait().unwrap()); let discriminant_def_id = assoc_items.in_definition_order().next().unwrap().def_id; tcx.mk_projection(discriminant_def_id, tcx.mk_substs([self.into()].iter())) } 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::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. pub fn ptr_metadata_ty(&'tcx self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { // FIXME: should this normalize? let tail = tcx.struct_tail_without_normalization(self); 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::Array(..) | ty::Closure(..) | ty::Never | ty::Error(_) | 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, ty::Str | ty::Slice(_) => tcx.types.usize, ty::Dynamic(..) => { let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap(); tcx.type_of(dyn_metadata).subst(tcx, &[tail.into()]) }, ty::Projection(_) | ty::Param(_) | ty::Opaque(..) | 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) } } } /// 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 /// `tcx.closure_kind_ty(closure_kind)`. /// /// 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 `src/librustc_typeck/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::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.expect_ty().is_trivially_sized(tcx)), ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(), ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => 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) } } } }