| //! This module contains `TyKind` and its major components. |
| |
| #![allow(rustc::usage_of_ty_tykind)] |
| |
| use crate::hir; |
| use crate::hir::def_id::DefId; |
| use crate::infer::canonical::Canonical; |
| use crate::mir::interpret::ConstValue; |
| use crate::middle::region; |
| use polonius_engine::Atom; |
| use rustc_data_structures::indexed_vec::Idx; |
| use rustc_macros::HashStable; |
| use crate::ty::subst::{InternalSubsts, Subst, SubstsRef, Kind, UnpackedKind}; |
| use crate::ty::{self, AdtDef, Discr, DefIdTree, TypeFlags, Ty, TyCtxt, TypeFoldable}; |
| use crate::ty::{List, TyS, ParamEnvAnd, ParamEnv}; |
| use crate::ty::layout::VariantIdx; |
| use crate::util::captures::Captures; |
| use crate::mir::interpret::{Scalar, GlobalId}; |
| |
| use smallvec::SmallVec; |
| use std::borrow::Cow; |
| use std::cmp::Ordering; |
| use std::marker::PhantomData; |
| use std::ops::Range; |
| use rustc_target::spec::abi; |
| use syntax::ast::{self, Ident}; |
| use syntax::symbol::{kw, InternedString}; |
| |
| use self::InferTy::*; |
| use self::TyKind::*; |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, |
| Hash, Debug, RustcEncodable, RustcDecodable, HashStable)] |
| pub struct TypeAndMut<'tcx> { |
| pub ty: Ty<'tcx>, |
| pub mutbl: hir::Mutability, |
| } |
| |
| #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, |
| RustcEncodable, RustcDecodable, Copy, 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: BoundRegion, |
| } |
| |
| #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, |
| RustcEncodable, RustcDecodable, Copy, HashStable)] |
| pub enum BoundRegion { |
| /// 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, InternedString), |
| |
| /// Anonymous region for the implicit env pointer parameter |
| /// to a closure |
| BrEnv, |
| } |
| |
| impl BoundRegion { |
| pub fn is_named(&self) -> bool { |
| match *self { |
| BoundRegion::BrNamed(..) => true, |
| _ => false, |
| } |
| } |
| |
| /// 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 { |
| BoundRegion::BrAnon(var) => BoundVar::from_u32(var), |
| _ => bug!("bound region is not anonymous"), |
| } |
| } |
| } |
| |
| /// N.B., if you change this, you'll probably want to change the corresponding |
| /// AST structure in `libsyntax/ast.rs` as well. |
| #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, |
| RustcEncodable, RustcDecodable, HashStable, Debug)] |
| #[cfg_attr(not(bootstrap), 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(ast::IntTy), |
| |
| /// A primitive unsigned integer type. For example, `u32`. |
| Uint(ast::UintTy), |
| |
| /// A primitive floating-point type. For example, `f64`. |
| Float(ast::FloatTy), |
| |
| /// 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, defined with `trait`. |
| Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>), |
| |
| /// The anonymous type of a closure. Used to represent the type of |
| /// `|a| a`. |
| Closure(DefId, ClosureSubsts<'tcx>), |
| |
| /// The anonymous type of a generator. Used to represent the type of |
| /// `|a| yield a`. |
| Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability), |
| |
| /// A type representin the types stored inside a generator. |
| /// This should only appear in GeneratorInteriors. |
| GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>), |
| |
| /// 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, |
| /// `<T as Trait<..>>::N`. |
| Projection(ProjectionTy<'tcx>), |
| |
| /// A placeholder type used when we do not have enough information |
| /// to normalize the projection of an associated type to an |
| /// existing concrete type. Currently only used with chalk-engine. |
| UnnormalizedProjection(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<T>(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, |
| } |
| |
| // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger. |
| #[cfg(target_arch = "x86_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, U0...Uk> { |
| /// upvar0: U0, |
| /// ... |
| /// upvark: Uk |
| /// } |
| /// |
| /// where: |
| /// |
| /// - 'l0...'li and T0...Tj are the lifetime and type 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. |
| /// - U0...Uk are type parameters representing the types of its upvars |
| /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar, |
| /// and the up-var has the type `Foo`, then `Ui = &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, U0> { |
| /// data: U0 |
| /// } |
| /// |
| /// 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 |
| /// as extra type parameters? 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 the role of CK and CS are |
| /// different. CK represents the "yield type" and CS represents the |
| /// "return type" of the generator. |
| #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, |
| Debug, RustcEncodable, RustcDecodable, HashStable)] |
| pub struct ClosureSubsts<'tcx> { |
| /// Lifetime and type parameters from the enclosing function, |
| /// concatenated with 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()`. Note that these are subslices of the |
| /// parent slice and not canonical substs themselves. |
| struct SplitClosureSubsts<'tcx> { |
| closure_kind_ty: Ty<'tcx>, |
| closure_sig_ty: Ty<'tcx>, |
| upvar_kinds: &'tcx [Kind<'tcx>], |
| } |
| |
| impl<'tcx> ClosureSubsts<'tcx> { |
| /// Divides the closure substs into their respective |
| /// components. Single source of truth with respect to the |
| /// ordering. |
| fn split(self, def_id: DefId, tcx: TyCtxt<'_>) -> SplitClosureSubsts<'tcx> { |
| let generics = tcx.generics_of(def_id); |
| let parent_len = generics.parent_count; |
| SplitClosureSubsts { |
| closure_kind_ty: self.substs.type_at(parent_len), |
| closure_sig_ty: self.substs.type_at(parent_len + 1), |
| upvar_kinds: &self.substs[parent_len + 2..], |
| } |
| } |
| |
| #[inline] |
| pub fn upvar_tys( |
| self, |
| def_id: DefId, |
| tcx: TyCtxt<'_>, |
| ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { |
| let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx); |
| upvar_kinds.iter().map(|t| { |
| if let UnpackedKind::Type(ty) = t.unpack() { |
| ty |
| } else { |
| bug!("upvar should be type") |
| } |
| }) |
| } |
| |
| /// 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(def_id, substs)`. |
| pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> { |
| self.split(def_id, tcx).closure_kind_ty |
| } |
| |
| /// Returns the type representing the closure signature for this |
| /// closure; may contain type variables during inference. To get |
| /// the closure signature during inference, use |
| /// `infcx.fn_sig(def_id)`. |
| pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> { |
| self.split(def_id, tcx).closure_sig_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 closure_kind(self, def_id: DefId, tcx: TyCtxt<'tcx>) -> ty::ClosureKind { |
| self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap() |
| } |
| |
| /// Extracts the signature from the 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_sig()`. |
| pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'tcx>) -> ty::PolyFnSig<'tcx> { |
| let ty = self.closure_sig_ty(def_id, tcx); |
| match ty.sty { |
| ty::FnPtr(sig) => sig, |
| _ => bug!("closure_sig_ty is not a fn-ptr: {:?}", ty.sty), |
| } |
| } |
| } |
| |
| /// Similar to `ClosureSubsts`; see the above documentation for more. |
| #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, |
| RustcEncodable, RustcDecodable, HashStable)] |
| pub struct GeneratorSubsts<'tcx> { |
| pub substs: SubstsRef<'tcx>, |
| } |
| |
| struct SplitGeneratorSubsts<'tcx> { |
| yield_ty: Ty<'tcx>, |
| return_ty: Ty<'tcx>, |
| witness: Ty<'tcx>, |
| upvar_kinds: &'tcx [Kind<'tcx>], |
| } |
| |
| impl<'tcx> GeneratorSubsts<'tcx> { |
| fn split(self, def_id: DefId, tcx: TyCtxt<'_>) -> SplitGeneratorSubsts<'tcx> { |
| let generics = tcx.generics_of(def_id); |
| let parent_len = generics.parent_count; |
| SplitGeneratorSubsts { |
| yield_ty: self.substs.type_at(parent_len), |
| return_ty: self.substs.type_at(parent_len + 1), |
| witness: self.substs.type_at(parent_len + 2), |
| upvar_kinds: &self.substs[parent_len + 3..], |
| } |
| } |
| |
| /// 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, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> { |
| self.split(def_id, tcx).witness |
| } |
| |
| #[inline] |
| pub fn upvar_tys( |
| self, |
| def_id: DefId, |
| tcx: TyCtxt<'_>, |
| ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { |
| let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx); |
| upvar_kinds.iter().map(|t| { |
| if let UnpackedKind::Type(ty) = t.unpack() { |
| ty |
| } else { |
| bug!("upvar should be type") |
| } |
| }) |
| } |
| |
| /// Returns the type representing the yield type of the generator. |
| pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> { |
| self.split(def_id, tcx).yield_ty |
| } |
| |
| /// Returns the type representing the return type of the generator. |
| pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> { |
| self.split(def_id, tcx).return_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, def_id: DefId, tcx: TyCtxt<'_>) -> PolyGenSig<'tcx> { |
| ty::Binder::dummy(self.sig(def_id, tcx)) |
| } |
| |
| /// Returns the "generator signature", which consists of its yield |
| /// and return types. |
| pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_>) -> GenSig<'tcx> { |
| ty::GenSig { |
| yield_ty: self.yield_ty(def_id, tcx), |
| return_ty: self.return_ty(def_id, tcx), |
| } |
| } |
| } |
| |
| impl<'tcx> GeneratorSubsts<'tcx> { |
| /// Generator have not been resumed yet |
| pub const UNRESUMED: usize = 0; |
| /// Generator has returned / 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<VariantIdx> { |
| // FIXME requires optimized MIR |
| let num_variants = tcx.generator_layout(def_id).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( |
| &'tcx self, |
| def_id: DefId, |
| tcx: TyCtxt<'tcx>, |
| ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + 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`. |
| #[inline] |
| pub fn variant_name(&self, 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<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> { |
| let layout = tcx.generator_layout(def_id); |
| 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, def_id: DefId, tcx: TyCtxt<'tcx>) -> impl Iterator<Item = Ty<'tcx>> { |
| self.upvar_tys(def_id, tcx) |
| } |
| } |
| |
| #[derive(Debug, Copy, Clone)] |
| pub enum UpvarSubsts<'tcx> { |
| Closure(ClosureSubsts<'tcx>), |
| Generator(GeneratorSubsts<'tcx>), |
| } |
| |
| impl<'tcx> UpvarSubsts<'tcx> { |
| #[inline] |
| pub fn upvar_tys( |
| self, |
| def_id: DefId, |
| tcx: TyCtxt<'_>, |
| ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { |
| let upvar_kinds = match self { |
| UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds, |
| UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds, |
| }; |
| upvar_kinds.iter().map(|t| { |
| if let UnpackedKind::Type(ty) = t.unpack() { |
| ty |
| } else { |
| bug!("upvar should be type") |
| } |
| }) |
| } |
| } |
| |
| #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, |
| RustcEncodable, RustcDecodable, HashStable)] |
| 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<ExistentialPredicate<'tcx>> { |
| 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) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(), |
| ExistentialPredicate::Projection(p) => |
| ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))), |
| ExistentialPredicate::AutoTrait(did) => { |
| let trait_ref = Binder(ty::TraitRef { |
| def_id: did, |
| substs: tcx.mk_substs_trait(self_ty, &[]), |
| }); |
| trait_ref.to_predicate() |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {} |
| |
| impl<'tcx> List<ExistentialPredicate<'tcx>> { |
| /// 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<ExistentialTraitRef<'tcx>> { |
| match self[0] { |
| ExistentialPredicate::Trait(tr) => Some(tr), |
| _ => None |
| } |
| } |
| |
| pub fn principal_def_id(&self) -> Option<DefId> { |
| self.principal().map(|d| d.def_id) |
| } |
| |
| #[inline] |
| pub fn projection_bounds<'a>(&'a self) -> |
| impl Iterator<Item = ExistentialProjection<'tcx>> + 'a |
| { |
| self.iter().filter_map(|predicate| { |
| match *predicate { |
| ExistentialPredicate::Projection(p) => Some(p), |
| _ => None, |
| } |
| }) |
| } |
| |
| #[inline] |
| pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a { |
| self.iter().filter_map(|predicate| { |
| match *predicate { |
| ExistentialPredicate::AutoTrait(d) => Some(d), |
| _ => None |
| } |
| }) |
| } |
| } |
| |
| impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> { |
| pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> { |
| self.skip_binder().principal().map(Binder::bind) |
| } |
| |
| pub fn principal_def_id(&self) -> Option<DefId> { |
| self.skip_binder().principal_def_id() |
| } |
| |
| #[inline] |
| pub fn projection_bounds<'a>(&'a self) -> |
| impl Iterator<Item = PolyExistentialProjection<'tcx>> + 'a { |
| self.skip_binder().projection_bounds().map(Binder::bind) |
| } |
| |
| #[inline] |
| pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a { |
| self.skip_binder().auto_traits() |
| } |
| |
| pub fn iter<'a>(&'a self) |
| -> impl DoubleEndedIterator<Item = Binder<ExistentialPredicate<'tcx>>> + 'tcx { |
| self.skip_binder().iter().cloned().map(Binder::bind) |
| } |
| } |
| |
| /// 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<U> |
| /// |
| /// 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<U>`, but in |
| /// that case the `Self` parameter is absent from the substitutions. |
| /// |
| /// Note that a `TraitRef` introduces a level of region binding, to |
| /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>` |
| /// or higher-ranked object types. |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)] |
| 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: def_id, substs: substs } |
| } |
| |
| /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` 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 input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a { |
| // Select only the "input types" from a trait-reference. For |
| // now this is all the types that appear in the |
| // trait-reference, but it should eventually exclude |
| // associated types. |
| self.substs.types() |
| } |
| |
| 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<TraitRef<'tcx>>; |
| |
| impl<'tcx> PolyTraitRef<'tcx> { |
| pub fn self_ty(&self) -> Ty<'tcx> { |
| self.skip_binder().self_ty() |
| } |
| |
| pub fn def_id(&self) -> DefId { |
| self.skip_binder().def_id |
| } |
| |
| pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> { |
| // Note that we preserve binding levels |
| Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() }) |
| } |
| } |
| |
| /// 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, |
| RustcEncodable, RustcDecodable, HashStable)] |
| pub struct ExistentialTraitRef<'tcx> { |
| pub def_id: DefId, |
| pub substs: SubstsRef<'tcx>, |
| } |
| |
| impl<'tcx> ExistentialTraitRef<'tcx> { |
| pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b { |
| // Select only the "input types" from a trait-reference. For |
| // now this is all the types that appear in the |
| // trait-reference, but it should eventually exclude |
| // associated types. |
| self.substs.types() |
| } |
| |
| 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<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)) |
| } |
| } |
| |
| /// 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<TraitRef>`). Note that when we instantiate, |
| /// erase, or otherwise "discharge" these bound vars, we change the |
| /// type from `Binder<T>` to just `T` (see |
| /// e.g., `liberate_late_bound_regions`). |
| #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub struct Binder<T>(T); |
| |
| impl<T> Binder<T> { |
| /// 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<T> |
| 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<T> { |
| Binder(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<F, U>(&self, f: F) -> Binder<U> |
| where F: FnOnce(&T) -> U |
| { |
| self.as_ref().map_bound(f) |
| } |
| |
| pub fn map_bound<F, U>(self, f: F) -> Binder<U> |
| where F: FnOnce(T) -> U |
| { |
| Binder(f(self.0)) |
| } |
| |
| /// 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<T> |
| where T: TypeFoldable<'tcx> |
| { |
| if self.skip_binder().has_escaping_bound_vars() { |
| None |
| } else { |
| Some(self.skip_binder().clone()) |
| } |
| } |
| |
| /// 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<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R> |
| 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<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>) |
| where F: FnOnce(T) -> (U, V) |
| { |
| let (u, v) = f(self.0); |
| (Binder(u), Binder(v)) |
| } |
| } |
| |
| /// Represents the projection of an associated type. In explicit UFCS |
| /// form this would be written `<T as Trait<..>>::N`. |
| #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, |
| Hash, Debug, RustcEncodable, RustcDecodable, HashStable)] |
| 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> { |
| /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the |
| /// associated item named `item_name`. |
| pub fn from_ref_and_name( |
| tcx: TyCtxt<'_>, |
| trait_ref: ty::TraitRef<'tcx>, |
| item_name: Ident, |
| ) -> ProjectionTy<'tcx> { |
| let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| { |
| item.kind == ty::AssocKind::Type && |
| tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id) |
| }).unwrap().def_id; |
| |
| ProjectionTy { |
| substs: trait_ref.substs, |
| item_def_id, |
| } |
| } |
| |
| /// Extracts the underlying trait reference from this projection. |
| /// For example, if this is a projection of `<T as Iterator>::Item`, |
| /// then this function would return a `T: Iterator` trait reference. |
| pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::TraitRef<'tcx> { |
| let def_id = tcx.associated_item(self.item_def_id).container.id(); |
| ty::TraitRef { |
| def_id, |
| substs: self.substs, |
| } |
| } |
| |
| pub fn self_ty(&self) -> Ty<'tcx> { |
| self.substs.type_at(0) |
| } |
| } |
| |
| #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)] |
| pub struct GenSig<'tcx> { |
| pub yield_ty: Ty<'tcx>, |
| pub return_ty: Ty<'tcx>, |
| } |
| |
| pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>; |
| |
| impl<'tcx> PolyGenSig<'tcx> { |
| pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> { |
| self.map_bound_ref(|sig| sig.yield_ty) |
| } |
| pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> { |
| 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, RustcEncodable, RustcDecodable, HashStable)] |
| pub struct FnSig<'tcx> { |
| pub inputs_and_output: &'tcx List<Ty<'tcx>>, |
| 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<FnSig<'tcx>>; |
| |
| 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<Ty<'tcx>> { |
| self.map_bound_ref(|fn_sig| fn_sig.inputs()[index]) |
| } |
| pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> { |
| self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output) |
| } |
| #[inline] |
| pub fn output(&self) -> ty::Binder<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<FnSig<'tcx>>>; |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, |
| Hash, RustcEncodable, RustcDecodable, HashStable)] |
| pub struct ParamTy { |
| pub index: u32, |
| pub name: InternedString, |
| } |
| |
| impl<'tcx> ParamTy { |
| pub fn new(index: u32, name: InternedString) -> ParamTy { |
| ParamTy { index, name: name } |
| } |
| |
| pub fn for_self() -> ParamTy { |
| ParamTy::new(0, kw::SelfUpper.as_interned_str()) |
| } |
| |
| pub fn for_def(def: &ty::GenericParamDef) -> ParamTy { |
| ParamTy::new(def.index, def.name) |
| } |
| |
| pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
| tcx.mk_ty_param(self.index, self.name) |
| } |
| } |
| |
| #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable, |
| Eq, PartialEq, Ord, PartialOrd, HashStable)] |
| pub struct ParamConst { |
| pub index: u32, |
| pub name: InternedString, |
| } |
| |
| impl<'tcx> ParamConst { |
| pub fn new(index: u32, name: InternedString) -> 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 Const<'tcx> { |
| tcx.mk_const_param(self.index, self.name, ty) |
| } |
| } |
| |
| newtype_index! { |
| /// A [De Bruijn index][dbi] is a standard means of representing |
| /// regions (and perhaps later types) in a higher-ranked setting. In |
| /// particular, imagine a type like this: |
| /// |
| /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char) |
| /// ^ ^ | | | |
| /// | | | | | |
| /// | +------------+ 0 | | |
| /// | | | |
| /// +--------------------------------+ 1 | |
| /// | | |
| /// +------------------------------------------+ 0 |
| /// |
| /// In this type, there are two binders (the outer fn and the inner |
| /// fn). We need to be able to determine, for any given region, which |
| /// fn type it is bound by, the inner or the outer one. There are |
| /// various ways you can do this, but a De Bruijn index is one of the |
| /// more convenient and has some nice properties. The basic idea is to |
| /// count the number of binders, inside out. Some examples should help |
| /// clarify what I mean. |
| /// |
| /// Let's start with the reference type `&'b isize` that is the first |
| /// argument to the inner function. This region `'b` is assigned a De |
| /// Bruijn index of 0, meaning "the innermost binder" (in this case, a |
| /// fn). The region `'a` that appears in the second argument type (`&'a |
| /// isize`) would then be assigned a De Bruijn index of 1, meaning "the |
| /// second-innermost binder". (These indices are written on the arrays |
| /// in the diagram). |
| /// |
| /// What is interesting is that De Bruijn index attached to a particular |
| /// variable will vary depending on where it appears. For example, |
| /// the final type `&'a char` also refers to the region `'a` declared on |
| /// the outermost fn. But this time, this reference is not nested within |
| /// any other binders (i.e., it is not an argument to the inner fn, but |
| /// rather the outer one). Therefore, in this case, it is assigned a |
| /// De Bruijn index of 0, because the innermost binder in that location |
| /// is the outer fn. |
| /// |
| /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index |
| pub struct DebruijnIndex { |
| DEBUG_FORMAT = "DebruijnIndex({})", |
| const INNERMOST = 0, |
| } |
| } |
| |
| pub type Region<'tcx> = &'tcx RegionKind; |
| |
| /// Representation of regions. |
| /// |
| /// Unlike types, most region variants are "fictitious", not concrete, |
| /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only |
| /// ones representing concrete regions. |
| /// |
| /// ## 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 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 guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html |
| #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, 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(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), |
| |
| /// A concrete region naming some statically determined scope |
| /// (e.g., an expression or sequence of statements) within the |
| /// current function. |
| ReScope(region::Scope), |
| |
| /// 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. |
| /// Bottom in the region lattice. We treat ReEmpty somewhat |
| /// specially; at least right now, we do not generate instances of |
| /// it during the GLB computations, but rather |
| /// generate an error instead. This is to improve error messages. |
| /// The only way to get an instance of ReEmpty is to have a region |
| /// variable with no constraints. |
| ReEmpty, |
| |
| /// Erased region, used by trait selection, in MIR and during codegen. |
| ReErased, |
| |
| /// These are regions bound in the "defining type" for a |
| /// closure. They are used ONLY as part of the |
| /// `ClosureRegionRequirements` that are produced by MIR borrowck. |
| /// See `ClosureRegionRequirements` for more details. |
| ReClosureBound(RegionVid), |
| } |
| |
| impl<'tcx> rustc_serialize::UseSpecializedDecodable for Region<'tcx> {} |
| |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)] |
| pub struct EarlyBoundRegion { |
| pub def_id: DefId, |
| pub index: u32, |
| pub name: InternedString, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
| pub struct TyVid { |
| pub index: u32, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
| pub struct ConstVid<'tcx> { |
| pub index: u32, |
| pub phantom: PhantomData<&'tcx ()>, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
| pub struct IntVid { |
| pub index: u32, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
| pub struct FloatVid { |
| pub index: u32, |
| } |
| |
| newtype_index! { |
| pub struct RegionVid { |
| DEBUG_FORMAT = custom, |
| } |
| } |
| |
| impl Atom for RegionVid { |
| fn index(self) -> usize { |
| Idx::index(self) |
| } |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, |
| Hash, RustcEncodable, RustcDecodable, HashStable)] |
| pub enum InferTy { |
| TyVar(TyVid), |
| IntVar(IntVid), |
| FloatVar(FloatVid), |
| |
| /// A `FreshTy` is one that is generated as a replacement for an |
| /// unbound type variable. This is convenient for caching etc. See |
| /// `infer::freshen` for more details. |
| FreshTy(u32), |
| FreshIntTy(u32), |
| FreshFloatTy(u32), |
| } |
| |
| newtype_index! { |
| pub struct BoundVar { .. } |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub struct BoundTy { |
| pub var: BoundVar, |
| pub kind: BoundTyKind, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub enum BoundTyKind { |
| Anon, |
| Param(InternedString), |
| } |
| |
| impl_stable_hash_for!(struct BoundTy { var, kind }); |
| impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) }); |
| |
| impl From<BoundVar> 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, RustcEncodable, RustcDecodable, HashStable)] |
| pub struct ExistentialProjection<'tcx> { |
| pub item_def_id: DefId, |
| pub substs: SubstsRef<'tcx>, |
| pub ty: Ty<'tcx>, |
| } |
| |
| pub type PolyExistentialProjection<'tcx> = Binder<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. <T as Iterator>::Item == X`, |
| /// then this function would return a `exists T. T: Iterator` existential trait |
| /// reference. |
| pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::ExistentialTraitRef<'tcx> { |
| let def_id = tcx.associated_item(self.item_def_id).container.id(); |
| ty::ExistentialTraitRef{ |
| def_id, |
| substs: self.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, |
| } |
| } |
| } |
| |
| 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 { |
| return self.skip_binder().item_def_id; |
| } |
| } |
| |
| impl DebruijnIndex { |
| /// Returns the resulting index when this value is moved into |
| /// `amount` number of new binders. So, e.g., if you had |
| /// |
| /// for<'a> fn(&'a x) |
| /// |
| /// and you wanted to change it to |
| /// |
| /// for<'a> fn(for<'b> fn(&'a x)) |
| /// |
| /// you would need to shift the index for `'a` into a new binder. |
| #[must_use] |
| pub fn shifted_in(self, amount: u32) -> DebruijnIndex { |
| DebruijnIndex::from_u32(self.as_u32() + amount) |
| } |
| |
| /// Update this index in place by shifting it "in" through |
| /// `amount` number of binders. |
| pub fn shift_in(&mut self, amount: u32) { |
| *self = self.shifted_in(amount); |
| } |
| |
| /// Returns the resulting index when this value is moved out from |
| /// `amount` number of new binders. |
| #[must_use] |
| pub fn shifted_out(self, amount: u32) -> DebruijnIndex { |
| DebruijnIndex::from_u32(self.as_u32() - amount) |
| } |
| |
| /// Update in place by shifting out from `amount` binders. |
| pub fn shift_out(&mut self, amount: u32) { |
| *self = self.shifted_out(amount); |
| } |
| |
| /// 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: DebruijnIndex) -> Self { |
| self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32()) |
| } |
| } |
| |
| impl_stable_hash_for!(struct DebruijnIndex { private }); |
| |
| /// 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.is_named(), |
| RegionKind::ReFree(fr) => fr.bound_region.is_named(), |
| RegionKind::ReScope(..) => false, |
| RegionKind::ReStatic => true, |
| RegionKind::ReVar(..) => false, |
| RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(), |
| RegionKind::ReEmpty => false, |
| RegionKind::ReErased => false, |
| RegionKind::ReClosureBound(..) => false, |
| } |
| } |
| |
| pub fn is_late_bound(&self) -> bool { |
| match *self { |
| ty::ReLateBound(..) => true, |
| _ => false, |
| } |
| } |
| |
| pub fn is_placeholder(&self) -> bool { |
| match *self { |
| ty::RePlaceholder(..) => true, |
| _ => false, |
| } |
| } |
| |
| pub fn bound_at_or_above_binder(&self, index: 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 keep_in_local_tcx(&self) -> bool { |
| if let ty::ReVar(..) = self { |
| true |
| } else { |
| false |
| } |
| } |
| |
| pub fn type_flags(&self) -> TypeFlags { |
| let mut flags = TypeFlags::empty(); |
| |
| if self.keep_in_local_tcx() { |
| flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX; |
| } |
| |
| match *self { |
| ty::ReVar(..) => { |
| flags = flags | TypeFlags::HAS_FREE_REGIONS; |
| flags = flags | TypeFlags::HAS_RE_INFER; |
| } |
| ty::RePlaceholder(..) => { |
| flags = flags | TypeFlags::HAS_FREE_REGIONS; |
| flags = flags | TypeFlags::HAS_RE_PLACEHOLDER; |
| } |
| ty::ReLateBound(..) => { |
| flags = flags | TypeFlags::HAS_RE_LATE_BOUND; |
| } |
| ty::ReEarlyBound(..) => { |
| flags = flags | TypeFlags::HAS_FREE_REGIONS; |
| flags = flags | TypeFlags::HAS_RE_EARLY_BOUND; |
| } |
| ty::ReEmpty | |
| ty::ReStatic | |
| ty::ReFree { .. } | |
| ty::ReScope { .. } => { |
| flags = flags | TypeFlags::HAS_FREE_REGIONS; |
| } |
| ty::ReErased => { |
| } |
| ty::ReClosureBound(..) => { |
| flags = flags | TypeFlags::HAS_FREE_REGIONS; |
| } |
| } |
| |
| match *self { |
| ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (), |
| _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES, |
| } |
| |
| 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] |
| pub fn is_unit(&self) -> bool { |
| match self.sty { |
| Tuple(ref tys) => tys.is_empty(), |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_never(&self) -> bool { |
| match self.sty { |
| Never => true, |
| _ => false, |
| } |
| } |
| |
| /// Checks whether a type is definitely uninhabited. This is |
| /// conservative: for some types that are uninhabited we return `false`, |
| /// but we only return `true` for types that are definitely uninhabited. |
| /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty` |
| /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero |
| /// size, to account for partial initialisation. See #49298 for details.) |
| pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool { |
| // FIXME(varkor): we can make this less conversative by substituting concrete |
| // type arguments. |
| match self.sty { |
| ty::Never => true, |
| ty::Adt(def, _) if def.is_union() => { |
| // For now, `union`s are never considered uninhabited. |
| false |
| } |
| ty::Adt(def, _) => { |
| // Any ADT is uninhabited if either: |
| // (a) It has no variants (i.e. an empty `enum`); |
| // (b) Each of its variants (a single one in the case of a `struct`) has at least |
| // one uninhabited field. |
| def.variants.iter().all(|var| { |
| var.fields.iter().any(|field| { |
| tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx) |
| }) |
| }) |
| } |
| ty::Tuple(..) => self.tuple_fields().any(|ty| { |
| ty.conservative_is_privately_uninhabited(tcx) |
| }), |
| ty::Array(ty, len) => { |
| match len.try_eval_usize(tcx, ParamEnv::empty()) { |
| // If the array is definitely non-empty, it's uninhabited if |
| // the type of its elements is uninhabited. |
| Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx), |
| _ => false |
| } |
| } |
| ty::Ref(..) => { |
| // References to uninitialised memory is valid for any type, including |
| // uninhabited types, in unsafe code, so we treat all references as |
| // inhabited. |
| false |
| } |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_primitive(&self) -> bool { |
| match self.sty { |
| Bool | Char | Int(_) | Uint(_) | Float(_) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_ty_var(&self) -> bool { |
| match self.sty { |
| Infer(TyVar(_)) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_ty_infer(&self) -> bool { |
| match self.sty { |
| Infer(_) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_phantom_data(&self) -> bool { |
| if let Adt(def, _) = self.sty { |
| def.is_phantom_data() |
| } else { |
| false |
| } |
| } |
| |
| #[inline] |
| pub fn is_bool(&self) -> bool { self.sty == Bool } |
| |
| #[inline] |
| pub fn is_param(&self, index: u32) -> bool { |
| match self.sty { |
| ty::Param(ref data) => data.index == index, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_slice(&self) -> bool { |
| match self.sty { |
| RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty { |
| Slice(_) | Str => true, |
| _ => false, |
| }, |
| _ => false |
| } |
| } |
| |
| #[inline] |
| pub fn is_simd(&self) -> bool { |
| match self.sty { |
| Adt(def, _) => def.repr.simd(), |
| _ => false, |
| } |
| } |
| |
| pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
| match self.sty { |
| Array(ty, _) | Slice(ty) => ty, |
| Str => tcx.mk_mach_uint(ast::UintTy::U8), |
| _ => bug!("sequence_element_type called on non-sequence value: {}", self), |
| } |
| } |
| |
| pub fn simd_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
| match self.sty { |
| Adt(def, substs) => { |
| def.non_enum_variant().fields[0].ty(tcx, substs) |
| } |
| _ => bug!("simd_type called on invalid type") |
| } |
| } |
| |
| pub fn simd_size(&self, _cx: TyCtxt<'_>) -> usize { |
| match self.sty { |
| Adt(def, _) => def.non_enum_variant().fields.len(), |
| _ => bug!("simd_size called on invalid type") |
| } |
| } |
| |
| #[inline] |
| pub fn is_region_ptr(&self) -> bool { |
| match self.sty { |
| Ref(..) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_mutable_ptr(&self) -> bool { |
| match self.sty { |
| RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) | |
| Ref(_, _, hir::Mutability::MutMutable) => true, |
| _ => false |
| } |
| } |
| |
| #[inline] |
| pub fn is_unsafe_ptr(&self) -> bool { |
| match self.sty { |
| RawPtr(_) => return true, |
| _ => return false, |
| } |
| } |
| |
| /// 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() |
| } |
| |
| /// Returns `true` if this type is an `Arc<T>`. |
| #[inline] |
| pub fn is_arc(&self) -> bool { |
| match self.sty { |
| Adt(def, _) => def.is_arc(), |
| _ => false, |
| } |
| } |
| |
| /// Returns `true` if this type is an `Rc<T>`. |
| #[inline] |
| pub fn is_rc(&self) -> bool { |
| match self.sty { |
| Adt(def, _) => def.is_rc(), |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_box(&self) -> bool { |
| match self.sty { |
| Adt(def, _) => def.is_box(), |
| _ => false, |
| } |
| } |
| |
| /// panics if called on any type other than `Box<T>` |
| pub fn boxed_ty(&self) -> Ty<'tcx> { |
| match self.sty { |
| 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 { |
| match self.sty { |
| Bool | Char | Int(_) | Float(_) | Uint(_) | |
| Infer(IntVar(_)) | Infer(FloatVar(_)) | |
| FnDef(..) | FnPtr(_) | RawPtr(_) => true, |
| _ => false |
| } |
| } |
| |
| /// Returns `true` if this type is a floating point type. |
| #[inline] |
| pub fn is_floating_point(&self) -> bool { |
| match self.sty { |
| Float(_) | |
| Infer(FloatVar(_)) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_trait(&self) -> bool { |
| match self.sty { |
| Dynamic(..) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_enum(&self) -> bool { |
| match self.sty { |
| Adt(adt_def, _) => { |
| adt_def.is_enum() |
| } |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_closure(&self) -> bool { |
| match self.sty { |
| Closure(..) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_generator(&self) -> bool { |
| match self.sty { |
| Generator(..) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_integral(&self) -> bool { |
| match self.sty { |
| Infer(IntVar(_)) | Int(_) | Uint(_) => true, |
| _ => false |
| } |
| } |
| |
| #[inline] |
| pub fn is_fresh_ty(&self) -> bool { |
| match self.sty { |
| Infer(FreshTy(_)) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_fresh(&self) -> bool { |
| match self.sty { |
| Infer(FreshTy(_)) => true, |
| Infer(FreshIntTy(_)) => true, |
| Infer(FreshFloatTy(_)) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_char(&self) -> bool { |
| match self.sty { |
| Char => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_numeric(&self) -> bool { |
| self.is_integral() || self.is_floating_point() |
| } |
| |
| #[inline] |
| pub fn is_signed(&self) -> bool { |
| match self.sty { |
| Int(_) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_ptr_sized_integral(&self) -> bool { |
| match self.sty { |
| Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_machine(&self) -> bool { |
| match self.sty { |
| Int(..) | Uint(..) | Float(..) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn has_concrete_skeleton(&self) -> bool { |
| match self.sty { |
| Param(_) | Infer(_) | Error => false, |
| _ => true, |
| } |
| } |
| |
| /// 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<TypeAndMut<'tcx>> { |
| match self.sty { |
| Adt(def, _) if def.is_box() => { |
| Some(TypeAndMut { |
| ty: self.boxed_ty(), |
| mutbl: hir::MutImmutable, |
| }) |
| }, |
| Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }), |
| RawPtr(mt) if explicit => Some(mt), |
| _ => None, |
| } |
| } |
| |
| /// Returns the type of `ty[i]`. |
| pub fn builtin_index(&self) -> Option<Ty<'tcx>> { |
| match self.sty { |
| Array(ty, _) | Slice(ty) => Some(ty), |
| _ => None, |
| } |
| } |
| |
| pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> { |
| match self.sty { |
| 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 `closure_sig()` not `fn_sig()`", |
| ), |
| _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self) |
| } |
| } |
| |
| #[inline] |
| pub fn is_fn(&self) -> bool { |
| match self.sty { |
| FnDef(..) | FnPtr(_) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_fn_ptr(&self) -> bool { |
| match self.sty { |
| FnPtr(_) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn is_impl_trait(&self) -> bool { |
| match self.sty { |
| Opaque(..) => true, |
| _ => false, |
| } |
| } |
| |
| #[inline] |
| pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> { |
| match self.sty { |
| Adt(adt, _) => Some(adt), |
| _ => None, |
| } |
| } |
| |
| /// Iterates over tuple fields. |
| /// Panics when called on anything but a tuple. |
| pub fn tuple_fields(&self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> { |
| match self.sty { |
| Tuple(substs) => substs.iter().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<Range<VariantIdx>> { |
| match self.sty { |
| TyKind::Adt(adt, _) => Some(adt.variant_range()), |
| TyKind::Generator(def_id, substs, _) => Some(substs.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<Discr<'tcx>> { |
| match self.sty { |
| TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)), |
| TyKind::Generator(def_id, substs, _) => |
| Some(substs.discriminant_for_variant(def_id, tcx, variant_index)), |
| _ => None, |
| } |
| } |
| |
| /// Push onto `out` the regions directly referenced from this type (but not |
| /// types reachable from this type via `walk_tys`). This ignores late-bound |
| /// regions binders. |
| pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) { |
| match self.sty { |
| Ref(region, _, _) => { |
| out.push(region); |
| } |
| Dynamic(ref obj, region) => { |
| out.push(region); |
| if let Some(principal) = obj.principal() { |
| out.extend(principal.skip_binder().substs.regions()); |
| } |
| } |
| Adt(_, substs) | Opaque(_, substs) => { |
| out.extend(substs.regions()) |
| } |
| Closure(_, ClosureSubsts { ref substs }) | |
| Generator(_, GeneratorSubsts { ref substs }, _) => { |
| out.extend(substs.regions()) |
| } |
| Projection(ref data) | UnnormalizedProjection(ref data) => { |
| out.extend(data.substs.regions()) |
| } |
| FnDef(..) | |
| FnPtr(_) | |
| GeneratorWitness(..) | |
| Bool | |
| Char | |
| Int(_) | |
| Uint(_) | |
| Float(_) | |
| Str | |
| Array(..) | |
| Slice(_) | |
| RawPtr(_) | |
| Never | |
| Tuple(..) | |
| Foreign(..) | |
| Param(_) | |
| Bound(..) | |
| Placeholder(..) | |
| Infer(_) | |
| Error => {} |
| } |
| } |
| |
| /// 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<ty::ClosureKind> { |
| match self.sty { |
| Int(int_ty) => match int_ty { |
| ast::IntTy::I8 => Some(ty::ClosureKind::Fn), |
| ast::IntTy::I16 => Some(ty::ClosureKind::FnMut), |
| ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce), |
| _ => bug!("cannot convert type `{:?}` to a closure kind", self), |
| }, |
| |
| 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. |
| pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool { |
| match self.sty { |
| ty::Infer(ty::IntVar(_)) | ty::Infer(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::UnnormalizedProjection(..) => bug!("only used with chalk-engine"), |
| |
| ty::Infer(ty::TyVar(_)) => false, |
| |
| ty::Bound(..) | |
| ty::Placeholder(..) | |
| ty::Infer(ty::FreshTy(_)) | |
| ty::Infer(ty::FreshIntTy(_)) | |
| ty::Infer(ty::FreshFloatTy(_)) => |
| bug!("is_trivially_sized applied to unexpected type: {:?}", self), |
| } |
| } |
| } |
| |
| /// Typed constant value. |
| #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, |
| Eq, PartialEq, Ord, PartialOrd, HashStable)] |
| pub struct Const<'tcx> { |
| pub ty: Ty<'tcx>, |
| |
| pub val: ConstValue<'tcx>, |
| } |
| |
| #[cfg(target_arch = "x86_64")] |
| static_assert_size!(Const<'_>, 40); |
| |
| impl<'tcx> Const<'tcx> { |
| #[inline] |
| pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self { |
| tcx.mk_const(Self { |
| val: ConstValue::Scalar(val), |
| ty, |
| }) |
| } |
| |
| #[inline] |
| pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self { |
| let size = tcx.layout_of(ty).unwrap_or_else(|e| { |
| panic!("could not compute layout for {:?}: {:?}", ty, e) |
| }).size; |
| Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value) |
| } |
| |
| #[inline] |
| pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self { |
| Self::from_scalar(tcx, Scalar::zst(), ty) |
| } |
| |
| #[inline] |
| pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self { |
| Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool)) |
| } |
| |
| #[inline] |
| pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self { |
| Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize)) |
| } |
| |
| #[inline] |
| pub fn try_eval_bits( |
| &self, |
| tcx: TyCtxt<'tcx>, |
| param_env: ParamEnv<'tcx>, |
| ty: Ty<'tcx>, |
| ) -> Option<u128> { |
| assert_eq!(self.ty, ty); |
| // if `ty` does not depend on generic parameters, use an empty param_env |
| let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size; |
| self.eval(tcx, param_env).val.try_to_bits(size) |
| } |
| |
| #[inline] |
| pub fn eval( |
| &self, |
| tcx: TyCtxt<'tcx>, |
| param_env: ParamEnv<'tcx>, |
| ) -> &Const<'tcx> { |
| // FIXME(const_generics): this doesn't work right now, |
| // because it tries to relate an `Infer` to a `Param`. |
| match self.val { |
| ConstValue::Unevaluated(did, substs) => { |
| // if `substs` has no unresolved components, use and empty param_env |
| let (param_env, substs) = param_env.with_reveal_all().and(substs).into_parts(); |
| // try to resolve e.g. associated constants to their definition on an impl |
| let instance = match ty::Instance::resolve(tcx, param_env, did, substs) { |
| Some(instance) => instance, |
| None => return self, |
| }; |
| let gid = GlobalId { |
| instance, |
| promoted: None, |
| }; |
| tcx.const_eval(param_env.and(gid)).unwrap_or(self) |
| }, |
| _ => self, |
| } |
| } |
| |
| #[inline] |
| pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> { |
| self.try_eval_bits(tcx, param_env, tcx.types.bool).and_then(|v| match v { |
| 0 => Some(false), |
| 1 => Some(true), |
| _ => None, |
| }) |
| } |
| |
| #[inline] |
| pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> { |
| self.try_eval_bits(tcx, param_env, tcx.types.usize).map(|v| v as u64) |
| } |
| |
| #[inline] |
| pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 { |
| self.try_eval_bits(tcx, param_env, ty).unwrap_or_else(|| |
| bug!("expected bits of {:#?}, got {:#?}", ty, self)) |
| } |
| |
| #[inline] |
| pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 { |
| self.eval_bits(tcx, param_env, tcx.types.usize) as u64 |
| } |
| } |
| |
| impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {} |
| |
| /// An inference variable for a const, for use in const generics. |
| #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, |
| Ord, RustcEncodable, RustcDecodable, Hash, HashStable)] |
| pub enum InferConst<'tcx> { |
| /// Infer the value of the const. |
| Var(ConstVid<'tcx>), |
| /// A fresh const variable. See `infer::freshen` for more details. |
| Fresh(u32), |
| /// Canonicalized const variable, used only when preparing a trait query. |
| Canonical(DebruijnIndex, BoundVar), |
| } |