| // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! This module contains TypeVariants and its major components |
| |
| use middle::cstore; |
| use hir::def_id::DefId; |
| use middle::region; |
| use ty::subst::{self, Substs}; |
| use ty::{self, AdtDef, ToPredicate, TypeFlags, Ty, TyCtxt, TyS, TypeFoldable}; |
| use util::common::ErrorReported; |
| |
| use collections::enum_set::{self, EnumSet, CLike}; |
| use std::fmt; |
| use std::ops; |
| use std::mem; |
| use syntax::abi; |
| use syntax::ast::{self, Name}; |
| use syntax::parse::token::keywords; |
| |
| use serialize::{Decodable, Decoder, Encodable, Encoder}; |
| |
| use hir; |
| |
| use self::FnOutput::*; |
| use self::InferTy::*; |
| use self::TypeVariants::*; |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)] |
| pub struct TypeAndMut<'tcx> { |
| pub ty: Ty<'tcx>, |
| pub mutbl: hir::Mutability, |
| } |
| |
| #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, |
| RustcEncodable, RustcDecodable, Copy)] |
| /// A "free" region `fr` can be interpreted as "some region |
| /// at least as big as the scope `fr.scope`". |
| pub struct FreeRegion { |
| pub scope: region::CodeExtent, |
| pub bound_region: BoundRegion |
| } |
| |
| #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, |
| RustcEncodable, RustcDecodable, Copy)] |
| pub enum BoundRegion { |
| /// An anonymous region parameter for a given fn (&T) |
| BrAnon(u32), |
| |
| /// Named region parameters for functions (a in &'a T) |
| /// |
| /// The def-id is needed to distinguish free regions in |
| /// the event of shadowing. |
| BrNamed(DefId, Name, Issue32330), |
| |
| /// Fresh bound identifiers created during GLB computations. |
| BrFresh(u32), |
| |
| // Anonymous region for the implicit env pointer parameter |
| // to a closure |
| BrEnv |
| } |
| |
| /// True if this late-bound region is unconstrained, and hence will |
| /// become early-bound once #32330 is fixed. |
| #[derive(Copy, Clone, Debug, PartialEq, PartialOrd, Eq, Ord, Hash, |
| RustcEncodable, RustcDecodable)] |
| pub enum Issue32330 { |
| WontChange, |
| |
| /// this region will change from late-bound to early-bound once |
| /// #32330 is fixed. |
| WillChange { |
| /// fn where is region declared |
| fn_def_id: DefId, |
| |
| /// name of region; duplicates the info in BrNamed but convenient |
| /// to have it here, and this code is only temporary |
| region_name: ast::Name, |
| } |
| } |
| |
| // NB: If you change this, you'll probably want to change the corresponding |
| // AST structure in libsyntax/ast.rs as well. |
| #[derive(Clone, PartialEq, Eq, Hash, Debug)] |
| pub enum TypeVariants<'tcx> { |
| /// The primitive boolean type. Written as `bool`. |
| TyBool, |
| |
| /// The primitive character type; holds a Unicode scalar value |
| /// (a non-surrogate code point). Written as `char`. |
| TyChar, |
| |
| /// A primitive signed integer type. For example, `i32`. |
| TyInt(ast::IntTy), |
| |
| /// A primitive unsigned integer type. For example, `u32`. |
| TyUint(ast::UintTy), |
| |
| /// A primitive floating-point type. For example, `f64`. |
| TyFloat(ast::FloatTy), |
| |
| /// An enumerated type, defined with `enum`. |
| /// |
| /// Substs here, possibly against intuition, *may* contain `TyParam`s. |
| /// That is, even after substitution it is possible that there are type |
| /// variables. This happens when the `TyEnum` corresponds to an enum |
| /// definition and not a concrete use of it. This is true for `TyStruct` |
| /// as well. |
| TyEnum(AdtDef<'tcx>, &'tcx Substs<'tcx>), |
| |
| /// A structure type, defined with `struct`. |
| /// |
| /// See warning about substitutions for enumerated types. |
| TyStruct(AdtDef<'tcx>, &'tcx Substs<'tcx>), |
| |
| /// `Box<T>`; this is nominally a struct in the documentation, but is |
| /// special-cased internally. For example, it is possible to implicitly |
| /// move the contents of a box out of that box, and methods of any type |
| /// can have type `Box<Self>`. |
| TyBox(Ty<'tcx>), |
| |
| /// The pointee of a string slice. Written as `str`. |
| TyStr, |
| |
| /// An array with the given length. Written as `[T; n]`. |
| TyArray(Ty<'tcx>, usize), |
| |
| /// The pointee of an array slice. Written as `[T]`. |
| TySlice(Ty<'tcx>), |
| |
| /// A raw pointer. Written as `*mut T` or `*const T` |
| TyRawPtr(TypeAndMut<'tcx>), |
| |
| /// A reference; a pointer with an associated lifetime. Written as |
| /// `&a mut T` or `&'a T`. |
| TyRef(&'tcx Region, TypeAndMut<'tcx>), |
| |
| /// The anonymous type of a function declaration/definition. Each |
| /// function has a unique type. |
| TyFnDef(DefId, &'tcx Substs<'tcx>, &'tcx BareFnTy<'tcx>), |
| |
| /// A pointer to a function. Written as `fn() -> i32`. |
| /// FIXME: This is currently also used to represent the callee of a method; |
| /// see ty::MethodCallee etc. |
| TyFnPtr(&'tcx BareFnTy<'tcx>), |
| |
| /// A trait, defined with `trait`. |
| TyTrait(Box<TraitTy<'tcx>>), |
| |
| /// The anonymous type of a closure. Used to represent the type of |
| /// `|a| a`. |
| TyClosure(DefId, ClosureSubsts<'tcx>), |
| |
| /// A tuple type. For example, `(i32, bool)`. |
| TyTuple(&'tcx [Ty<'tcx>]), |
| |
| /// The projection of an associated type. For example, |
| /// `<T as Trait<..>>::N`. |
| TyProjection(ProjectionTy<'tcx>), |
| |
| /// A type parameter; for example, `T` in `fn f<T>(x: T) {} |
| TyParam(ParamTy), |
| |
| /// A type variable used during type-checking. |
| TyInfer(InferTy), |
| |
| /// A placeholder for a type which could not be computed; this is |
| /// propagated to avoid useless error messages. |
| TyError, |
| } |
| |
| /// A closure can be modeled as a struct that looks like: |
| /// |
| /// struct Closure<'l0...'li, T0...Tj, 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, and U0...Uk are |
| /// type parameters representing the types of its upvars (borrowed, if |
| /// appropriate). |
| /// |
| /// 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 extent of the closure itself; this is some |
| /// subset of `foo`, probably just the extent 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 trans 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 |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub struct ClosureSubsts<'tcx> { |
| /// Lifetime and type parameters from the enclosing function. |
| /// These are separated out because trans wants to pass them around |
| /// when monomorphizing. |
| pub func_substs: &'tcx Substs<'tcx>, |
| |
| /// The types of the upvars. The list parallels the freevars and |
| /// `upvar_borrows` lists. These are kept distinct so that we can |
| /// easily index into them. |
| pub upvar_tys: &'tcx [Ty<'tcx>] |
| } |
| |
| impl<'tcx> Encodable for ClosureSubsts<'tcx> { |
| fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> { |
| (self.func_substs, self.upvar_tys).encode(s) |
| } |
| } |
| |
| impl<'tcx> Decodable for ClosureSubsts<'tcx> { |
| fn decode<D: Decoder>(d: &mut D) -> Result<ClosureSubsts<'tcx>, D::Error> { |
| let (func_substs, upvar_tys) = Decodable::decode(d)?; |
| cstore::tls::with_decoding_context(d, |dcx, _| { |
| Ok(ClosureSubsts { |
| func_substs: func_substs, |
| upvar_tys: dcx.tcx().mk_type_list(upvar_tys) |
| }) |
| }) |
| } |
| } |
| |
| #[derive(Clone, PartialEq, Eq, Hash)] |
| pub struct TraitTy<'tcx> { |
| pub principal: ty::PolyTraitRef<'tcx>, |
| pub bounds: ExistentialBounds<'tcx>, |
| } |
| |
| impl<'a, 'gcx, 'tcx> TraitTy<'tcx> { |
| pub fn principal_def_id(&self) -> DefId { |
| self.principal.0.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 skolemized type. |
| pub fn principal_trait_ref_with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, |
| self_ty: Ty<'tcx>) |
| -> ty::PolyTraitRef<'tcx> |
| { |
| // otherwise the escaping regions would be captured by the binder |
| assert!(!self_ty.has_escaping_regions()); |
| |
| ty::Binder(TraitRef { |
| def_id: self.principal.0.def_id, |
| substs: tcx.mk_substs(self.principal.0.substs.with_self_ty(self_ty)), |
| }) |
| } |
| |
| pub fn projection_bounds_with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, |
| self_ty: Ty<'tcx>) |
| -> Vec<ty::PolyProjectionPredicate<'tcx>> |
| { |
| // otherwise the escaping regions would be captured by the binders |
| assert!(!self_ty.has_escaping_regions()); |
| |
| self.bounds.projection_bounds.iter() |
| .map(|in_poly_projection_predicate| { |
| let in_projection_ty = &in_poly_projection_predicate.0.projection_ty; |
| let substs = tcx.mk_substs(in_projection_ty.trait_ref.substs.with_self_ty(self_ty)); |
| let trait_ref = ty::TraitRef::new(in_projection_ty.trait_ref.def_id, |
| substs); |
| let projection_ty = ty::ProjectionTy { |
| trait_ref: trait_ref, |
| item_name: in_projection_ty.item_name |
| }; |
| ty::Binder(ty::ProjectionPredicate { |
| projection_ty: projection_ty, |
| ty: in_poly_projection_predicate.0.ty |
| }) |
| }) |
| .collect() |
| } |
| } |
| |
| /// 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 def-id is the |
| /// def-id for the trait `Foo` and the substs defines `T` as parameter 0 in the |
| /// `SelfSpace` and `U` as parameter 0 in the `TypeSpace`. |
| /// |
| /// 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)] |
| pub struct TraitRef<'tcx> { |
| pub def_id: DefId, |
| pub substs: &'tcx Substs<'tcx>, |
| } |
| |
| pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>; |
| |
| impl<'tcx> PolyTraitRef<'tcx> { |
| pub fn self_ty(&self) -> Ty<'tcx> { |
| self.0.self_ty() |
| } |
| |
| pub fn def_id(&self) -> DefId { |
| self.0.def_id |
| } |
| |
| pub fn substs(&self) -> &'tcx Substs<'tcx> { |
| // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<> |
| self.0.substs |
| } |
| |
| pub fn input_types(&self) -> &[Ty<'tcx>] { |
| // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<> |
| self.0.input_types() |
| } |
| |
| pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> { |
| // Note that we preserve binding levels |
| Binder(ty::TraitPredicate { trait_ref: self.0.clone() }) |
| } |
| } |
| |
| /// Binder is a binder for higher-ranked lifetimes. 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 skolemize, instantiate, |
| /// erase, or otherwise "discharge" these bound regions, we change the |
| /// type from `Binder<T>` to just `T` (see |
| /// e.g. `liberate_late_bound_regions`). |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub struct Binder<T>(pub T); |
| |
| impl<T> Binder<T> { |
| /// Skips the binder and returns the "bound" value. This is a |
| /// risky thing to do because it's easy to get confused about |
| /// debruijn indices and the like. It is usually better to |
| /// discharge the binder using `no_late_bound_regions` 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 regions, 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 def-id 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> { |
| ty::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 |
| { |
| ty::Binder(f(self.0)) |
| } |
| } |
| |
| impl fmt::Debug for TypeFlags { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| write!(f, "{}", self.bits) |
| } |
| } |
| |
| /// Represents the projection of an associated type. In explicit UFCS |
| /// form this would be written `<T as Trait<..>>::N`. |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub struct ProjectionTy<'tcx> { |
| /// The trait reference `T as Trait<..>`. |
| pub trait_ref: ty::TraitRef<'tcx>, |
| |
| /// The name `N` of the associated type. |
| pub item_name: Name, |
| } |
| |
| impl<'tcx> ProjectionTy<'tcx> { |
| pub fn sort_key(&self) -> (DefId, Name) { |
| (self.trait_ref.def_id, self.item_name) |
| } |
| } |
| |
| #[derive(Clone, PartialEq, Eq, Hash, Debug)] |
| pub struct BareFnTy<'tcx> { |
| pub unsafety: hir::Unsafety, |
| pub abi: abi::Abi, |
| pub sig: PolyFnSig<'tcx>, |
| } |
| |
| #[derive(Clone, PartialEq, Eq, Hash)] |
| pub struct ClosureTy<'tcx> { |
| pub unsafety: hir::Unsafety, |
| pub abi: abi::Abi, |
| pub sig: PolyFnSig<'tcx>, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] |
| pub enum FnOutput<'tcx> { |
| FnConverging(Ty<'tcx>), |
| FnDiverging |
| } |
| |
| impl<'tcx> FnOutput<'tcx> { |
| pub fn diverges(&self) -> bool { |
| *self == FnDiverging |
| } |
| |
| pub fn unwrap(self) -> Ty<'tcx> { |
| match self { |
| ty::FnConverging(t) => t, |
| ty::FnDiverging => bug!() |
| } |
| } |
| |
| pub fn unwrap_or(self, def: Ty<'tcx>) -> Ty<'tcx> { |
| match self { |
| ty::FnConverging(t) => t, |
| ty::FnDiverging => def |
| } |
| } |
| |
| pub fn maybe_converging(self) -> Option<Ty<'tcx>> { |
| match self { |
| ty::FnConverging(t) => Some(t), |
| ty::FnDiverging => None |
| } |
| } |
| } |
| |
| pub type PolyFnOutput<'tcx> = Binder<FnOutput<'tcx>>; |
| |
| impl<'tcx> PolyFnOutput<'tcx> { |
| pub fn diverges(&self) -> bool { |
| self.0.diverges() |
| } |
| } |
| |
| /// Signature of a function type, which I 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. |
| /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns) |
| #[derive(Clone, PartialEq, Eq, Hash)] |
| pub struct FnSig<'tcx> { |
| pub inputs: Vec<Ty<'tcx>>, |
| pub output: FnOutput<'tcx>, |
| pub variadic: bool |
| } |
| |
| pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>; |
| |
| impl<'tcx> PolyFnSig<'tcx> { |
| pub fn inputs(&self) -> ty::Binder<Vec<Ty<'tcx>>> { |
| self.map_bound_ref(|fn_sig| fn_sig.inputs.clone()) |
| } |
| pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> { |
| self.map_bound_ref(|fn_sig| fn_sig.inputs[index]) |
| } |
| pub fn output(&self) -> ty::Binder<FnOutput<'tcx>> { |
| self.map_bound_ref(|fn_sig| fn_sig.output.clone()) |
| } |
| pub fn variadic(&self) -> bool { |
| self.skip_binder().variadic |
| } |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash)] |
| pub struct ParamTy { |
| pub space: subst::ParamSpace, |
| pub idx: u32, |
| pub name: Name, |
| } |
| |
| impl<'a, 'gcx, 'tcx> ParamTy { |
| pub fn new(space: subst::ParamSpace, |
| index: u32, |
| name: Name) |
| -> ParamTy { |
| ParamTy { space: space, idx: index, name: name } |
| } |
| |
| pub fn for_self() -> ParamTy { |
| ParamTy::new(subst::SelfSpace, 0, keywords::SelfType.name()) |
| } |
| |
| pub fn for_def(def: &ty::TypeParameterDef) -> ParamTy { |
| ParamTy::new(def.space, def.index, def.name) |
| } |
| |
| pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> { |
| tcx.mk_param(self.space, self.idx, self.name) |
| } |
| |
| pub fn is_self(&self) -> bool { |
| self.space == subst::SelfSpace && self.idx == 0 |
| } |
| } |
| |
| /// 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) |
| /// ^ ^ | | | |
| /// | | | | | |
| /// | +------------+ 1 | | |
| /// | | | |
| /// +--------------------------------+ 2 | |
| /// | | |
| /// +------------------------------------------+ 1 |
| /// |
| /// 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 1, 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 2, 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 1, because the innermost binder in that location |
| /// is the outer fn. |
| /// |
| /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index |
| #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, Copy)] |
| pub struct DebruijnIndex { |
| // We maintain the invariant that this is never 0. So 1 indicates |
| // the innermost binder. To ensure this, create with `DebruijnIndex::new`. |
| pub depth: u32, |
| } |
| |
| /// 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 2 kind of |
| /// bound regions: early-bound, which are bound in a TypeScheme/TraitDef, |
| /// and are substituted by a Substs, 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 TyParam-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 skolemized regions, free regions, |
| /// or region variables). |
| /// |
| /// ## Skolemized 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. |
| /// |
| /// The process of doing that is called "skolemization". The bound regions |
| /// are replaced by skolemized markers, which don't satisfy any relation |
| /// not explicity provided. |
| /// |
| /// There are 2 kinds of skolemized regions in rustc: `ReFree` and |
| /// `ReSkolemized`. 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`. |
| /// `ReSkolemized` is designed for this purpose. In these contexts, |
| /// there's also the risk that some inference variable laying around will |
| /// get unified with your skolemized region: if you want to check whether |
| /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a` |
| /// with a skolemized region `'%a`, the variable `'_` would just be |
| /// instantiated to the skolemized region `'%a`, which is wrong because |
| /// the inference variable is supposed to satisfy the relation |
| /// *for every value of the skolemized region*. To ensure that doesn't |
| /// happen, you can use `leak_check`. This is more clearly explained |
| /// by infer/higher_ranked/README.md. |
| /// |
| /// [1] http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/ |
| /// [2] http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/ |
| #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable)] |
| pub enum Region { |
| // 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 extent |
| /// (e.g. an expression or sequence of statements) within the |
| /// current function. |
| ReScope(region::CodeExtent), |
| |
| /// Static data that has an "infinite" lifetime. Top in the region lattice. |
| ReStatic, |
| |
| /// A region variable. Should not exist after typeck. |
| ReVar(RegionVid), |
| |
| /// A skolemized region - basically the higher-ranked version of ReFree. |
| /// Should not exist after typeck. |
| ReSkolemized(SkolemizedRegionVid, BoundRegion), |
| |
| /// 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 trans. |
| ReErased, |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug)] |
| pub struct EarlyBoundRegion { |
| pub space: subst::ParamSpace, |
| pub index: u32, |
| pub name: Name, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash)] |
| pub struct TyVid { |
| pub index: u32, |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash)] |
| pub struct IntVid { |
| pub index: u32 |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash)] |
| pub struct FloatVid { |
| pub index: u32 |
| } |
| |
| #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)] |
| pub struct RegionVid { |
| pub index: u32 |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] |
| pub struct SkolemizedRegionVid { |
| pub index: u32 |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash)] |
| 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) |
| } |
| |
| /// Bounds suitable for an existentially quantified type parameter |
| /// such as those that appear in object types or closure types. |
| #[derive(PartialEq, Eq, Hash, Clone)] |
| pub struct ExistentialBounds<'tcx> { |
| pub region_bound: ty::Region, |
| pub builtin_bounds: BuiltinBounds, |
| pub projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>, |
| } |
| |
| impl<'tcx> ExistentialBounds<'tcx> { |
| pub fn new(region_bound: ty::Region, |
| builtin_bounds: BuiltinBounds, |
| projection_bounds: Vec<ty::PolyProjectionPredicate<'tcx>>) |
| -> Self { |
| let mut projection_bounds = projection_bounds; |
| projection_bounds.sort_by(|a, b| a.sort_key().cmp(&b.sort_key())); |
| ExistentialBounds { |
| region_bound: region_bound, |
| builtin_bounds: builtin_bounds, |
| projection_bounds: projection_bounds |
| } |
| } |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)] |
| pub struct BuiltinBounds(EnumSet<BuiltinBound>); |
| |
| impl<'a, 'gcx, 'tcx> BuiltinBounds { |
| pub fn empty() -> BuiltinBounds { |
| BuiltinBounds(EnumSet::new()) |
| } |
| |
| pub fn iter(&self) -> enum_set::Iter<BuiltinBound> { |
| self.into_iter() |
| } |
| |
| pub fn to_predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, |
| self_ty: Ty<'tcx>) |
| -> Vec<ty::Predicate<'tcx>> { |
| self.iter().filter_map(|builtin_bound| |
| match tcx.trait_ref_for_builtin_bound(builtin_bound, self_ty) { |
| Ok(trait_ref) => Some(trait_ref.to_predicate()), |
| Err(ErrorReported) => { None } |
| } |
| ).collect() |
| } |
| } |
| |
| impl ops::Deref for BuiltinBounds { |
| type Target = EnumSet<BuiltinBound>; |
| fn deref(&self) -> &Self::Target { &self.0 } |
| } |
| |
| impl ops::DerefMut for BuiltinBounds { |
| fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } |
| } |
| |
| impl<'a> IntoIterator for &'a BuiltinBounds { |
| type Item = BuiltinBound; |
| type IntoIter = enum_set::Iter<BuiltinBound>; |
| fn into_iter(self) -> Self::IntoIter { |
| (**self).into_iter() |
| } |
| } |
| |
| #[derive(Clone, RustcEncodable, PartialEq, Eq, RustcDecodable, Hash, |
| Debug, Copy)] |
| #[repr(usize)] |
| pub enum BuiltinBound { |
| Send, |
| Sized, |
| Copy, |
| Sync, |
| } |
| |
| impl CLike for BuiltinBound { |
| fn to_usize(&self) -> usize { |
| *self as usize |
| } |
| fn from_usize(v: usize) -> BuiltinBound { |
| unsafe { mem::transmute(v) } |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { |
| pub fn try_add_builtin_trait(self, |
| trait_def_id: DefId, |
| builtin_bounds: &mut EnumSet<BuiltinBound>) |
| -> bool |
| { |
| //! Checks whether `trait_ref` refers to one of the builtin |
| //! traits, like `Send`, and adds the corresponding |
| //! bound to the set `builtin_bounds` if so. Returns true if `trait_ref` |
| //! is a builtin trait. |
| |
| match self.lang_items.to_builtin_kind(trait_def_id) { |
| Some(bound) => { builtin_bounds.insert(bound); true } |
| None => false |
| } |
| } |
| } |
| |
| impl DebruijnIndex { |
| pub fn new(depth: u32) -> DebruijnIndex { |
| assert!(depth > 0); |
| DebruijnIndex { depth: depth } |
| } |
| |
| pub fn shifted(&self, amount: u32) -> DebruijnIndex { |
| DebruijnIndex { depth: self.depth + amount } |
| } |
| } |
| |
| // Region utilities |
| impl Region { |
| pub fn is_bound(&self) -> bool { |
| match *self { |
| ty::ReEarlyBound(..) => true, |
| ty::ReLateBound(..) => true, |
| _ => false |
| } |
| } |
| |
| pub fn needs_infer(&self) -> bool { |
| match *self { |
| ty::ReVar(..) | ty::ReSkolemized(..) => true, |
| _ => false |
| } |
| } |
| |
| pub fn escapes_depth(&self, depth: u32) -> bool { |
| match *self { |
| ty::ReLateBound(debruijn, _) => debruijn.depth > depth, |
| _ => false, |
| } |
| } |
| |
| /// Returns the depth of `self` from the (1-based) binding level `depth` |
| pub fn from_depth(&self, depth: u32) -> Region { |
| match *self { |
| ty::ReLateBound(debruijn, r) => ty::ReLateBound(DebruijnIndex { |
| depth: debruijn.depth - (depth - 1) |
| }, r), |
| r => r |
| } |
| } |
| } |
| |
| // Type utilities |
| impl<'a, 'gcx, 'tcx> TyS<'tcx> { |
| pub fn as_opt_param_ty(&self) -> Option<ty::ParamTy> { |
| match self.sty { |
| ty::TyParam(ref d) => Some(d.clone()), |
| _ => None, |
| } |
| } |
| |
| pub fn is_nil(&self) -> bool { |
| match self.sty { |
| TyTuple(ref tys) => tys.is_empty(), |
| _ => false |
| } |
| } |
| |
| pub fn is_empty(&self, _cx: TyCtxt) -> bool { |
| // FIXME(#24885): be smarter here |
| match self.sty { |
| TyEnum(def, _) | TyStruct(def, _) => def.is_empty(), |
| _ => false |
| } |
| } |
| |
| pub fn is_primitive(&self) -> bool { |
| match self.sty { |
| TyBool | TyChar | TyInt(_) | TyUint(_) | TyFloat(_) => true, |
| _ => false, |
| } |
| } |
| |
| pub fn is_ty_var(&self) -> bool { |
| match self.sty { |
| TyInfer(TyVar(_)) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_phantom_data(&self) -> bool { |
| if let TyStruct(def, _) = self.sty { |
| def.is_phantom_data() |
| } else { |
| false |
| } |
| } |
| |
| pub fn is_bool(&self) -> bool { self.sty == TyBool } |
| |
| pub fn is_param(&self, space: subst::ParamSpace, index: u32) -> bool { |
| match self.sty { |
| ty::TyParam(ref data) => data.space == space && data.idx == index, |
| _ => false, |
| } |
| } |
| |
| pub fn is_self(&self) -> bool { |
| match self.sty { |
| TyParam(ref p) => p.space == subst::SelfSpace, |
| _ => false |
| } |
| } |
| |
| pub fn is_slice(&self) -> bool { |
| match self.sty { |
| TyRawPtr(mt) | TyRef(_, mt) => match mt.ty.sty { |
| TySlice(_) | TyStr => true, |
| _ => false, |
| }, |
| _ => false |
| } |
| } |
| |
| pub fn is_structural(&self) -> bool { |
| match self.sty { |
| TyStruct(..) | TyTuple(_) | TyEnum(..) | |
| TyArray(..) | TyClosure(..) => true, |
| _ => self.is_slice() | self.is_trait() |
| } |
| } |
| |
| #[inline] |
| pub fn is_simd(&self) -> bool { |
| match self.sty { |
| TyStruct(def, _) => def.is_simd(), |
| _ => false |
| } |
| } |
| |
| pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> { |
| match self.sty { |
| TyArray(ty, _) | TySlice(ty) => ty, |
| TyStr => tcx.mk_mach_uint(ast::UintTy::U8), |
| _ => bug!("sequence_element_type called on non-sequence value: {}", self), |
| } |
| } |
| |
| pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> { |
| match self.sty { |
| TyStruct(def, substs) => { |
| def.struct_variant().fields[0].ty(tcx, substs) |
| } |
| _ => bug!("simd_type called on invalid type") |
| } |
| } |
| |
| pub fn simd_size(&self, _cx: TyCtxt) -> usize { |
| match self.sty { |
| TyStruct(def, _) => def.struct_variant().fields.len(), |
| _ => bug!("simd_size called on invalid type") |
| } |
| } |
| |
| pub fn is_region_ptr(&self) -> bool { |
| match self.sty { |
| TyRef(..) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_unsafe_ptr(&self) -> bool { |
| match self.sty { |
| TyRawPtr(_) => return true, |
| _ => return false |
| } |
| } |
| |
| pub fn is_unique(&self) -> bool { |
| match self.sty { |
| TyBox(_) => true, |
| _ => false |
| } |
| } |
| |
| /* |
| A scalar type is one that denotes an atomic datum, with no sub-components. |
| (A TyRawPtr is scalar because it represents a non-managed pointer, so its |
| contents are abstract to rustc.) |
| */ |
| pub fn is_scalar(&self) -> bool { |
| match self.sty { |
| TyBool | TyChar | TyInt(_) | TyFloat(_) | TyUint(_) | |
| TyInfer(IntVar(_)) | TyInfer(FloatVar(_)) | |
| TyFnDef(..) | TyFnPtr(_) | TyRawPtr(_) => true, |
| _ => false |
| } |
| } |
| |
| /// Returns true if this type is a floating point type and false otherwise. |
| pub fn is_floating_point(&self) -> bool { |
| match self.sty { |
| TyFloat(_) | |
| TyInfer(FloatVar(_)) => true, |
| _ => false, |
| } |
| } |
| |
| pub fn is_trait(&self) -> bool { |
| match self.sty { |
| TyTrait(..) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_integral(&self) -> bool { |
| match self.sty { |
| TyInfer(IntVar(_)) | TyInt(_) | TyUint(_) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_fresh(&self) -> bool { |
| match self.sty { |
| TyInfer(FreshTy(_)) => true, |
| TyInfer(FreshIntTy(_)) => true, |
| TyInfer(FreshFloatTy(_)) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_uint(&self) -> bool { |
| match self.sty { |
| TyInfer(IntVar(_)) | TyUint(ast::UintTy::Us) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_char(&self) -> bool { |
| match self.sty { |
| TyChar => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_fp(&self) -> bool { |
| match self.sty { |
| TyInfer(FloatVar(_)) | TyFloat(_) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_numeric(&self) -> bool { |
| self.is_integral() || self.is_fp() |
| } |
| |
| pub fn is_signed(&self) -> bool { |
| match self.sty { |
| TyInt(_) => true, |
| _ => false |
| } |
| } |
| |
| pub fn is_machine(&self) -> bool { |
| match self.sty { |
| TyInt(ast::IntTy::Is) | TyUint(ast::UintTy::Us) => false, |
| TyInt(..) | TyUint(..) | TyFloat(..) => true, |
| _ => false |
| } |
| } |
| |
| pub fn has_concrete_skeleton(&self) -> bool { |
| match self.sty { |
| TyParam(_) | TyInfer(_) | TyError => 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, pref: ty::LvaluePreference) |
| -> Option<TypeAndMut<'tcx>> |
| { |
| match self.sty { |
| TyBox(ty) => { |
| Some(TypeAndMut { |
| ty: ty, |
| mutbl: if pref == ty::PreferMutLvalue { |
| hir::MutMutable |
| } else { |
| hir::MutImmutable |
| }, |
| }) |
| }, |
| TyRef(_, mt) => Some(mt), |
| TyRawPtr(mt) if explicit => Some(mt), |
| _ => None |
| } |
| } |
| |
| // Returns the type of ty[i] |
| pub fn builtin_index(&self) -> Option<Ty<'tcx>> { |
| match self.sty { |
| TyArray(ty, _) | TySlice(ty) => Some(ty), |
| _ => None |
| } |
| } |
| |
| pub fn fn_sig(&self) -> &'tcx PolyFnSig<'tcx> { |
| match self.sty { |
| TyFnDef(_, _, ref f) | TyFnPtr(ref f) => &f.sig, |
| _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self) |
| } |
| } |
| |
| /// Returns the ABI of the given function. |
| pub fn fn_abi(&self) -> abi::Abi { |
| match self.sty { |
| TyFnDef(_, _, ref f) | TyFnPtr(ref f) => f.abi, |
| _ => bug!("Ty::fn_abi() called on non-fn type"), |
| } |
| } |
| |
| // Type accessors for substructures of types |
| pub fn fn_args(&self) -> ty::Binder<Vec<Ty<'tcx>>> { |
| self.fn_sig().inputs() |
| } |
| |
| pub fn fn_ret(&self) -> Binder<FnOutput<'tcx>> { |
| self.fn_sig().output() |
| } |
| |
| pub fn is_fn(&self) -> bool { |
| match self.sty { |
| TyFnDef(..) | TyFnPtr(_) => true, |
| _ => false |
| } |
| } |
| |
| pub fn ty_to_def_id(&self) -> Option<DefId> { |
| match self.sty { |
| TyTrait(ref tt) => Some(tt.principal_def_id()), |
| TyStruct(def, _) | |
| TyEnum(def, _) => Some(def.did), |
| TyClosure(id, _) => Some(id), |
| _ => None |
| } |
| } |
| |
| pub fn ty_adt_def(&self) -> Option<AdtDef<'tcx>> { |
| match self.sty { |
| TyStruct(adt, _) | TyEnum(adt, _) => Some(adt), |
| _ => None |
| } |
| } |
| |
| /// Returns 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 regions(&self) -> Vec<ty::Region> { |
| match self.sty { |
| TyRef(region, _) => { |
| vec![*region] |
| } |
| TyTrait(ref obj) => { |
| let mut v = vec![obj.bounds.region_bound]; |
| v.extend_from_slice(obj.principal.skip_binder() |
| .substs.regions.as_slice()); |
| v |
| } |
| TyEnum(_, substs) | |
| TyStruct(_, substs) => { |
| substs.regions.as_slice().to_vec() |
| } |
| TyClosure(_, ref substs) => { |
| substs.func_substs.regions.as_slice().to_vec() |
| } |
| TyProjection(ref data) => { |
| data.trait_ref.substs.regions.as_slice().to_vec() |
| } |
| TyFnDef(..) | |
| TyFnPtr(_) | |
| TyBool | |
| TyChar | |
| TyInt(_) | |
| TyUint(_) | |
| TyFloat(_) | |
| TyBox(_) | |
| TyStr | |
| TyArray(_, _) | |
| TySlice(_) | |
| TyRawPtr(_) | |
| TyTuple(_) | |
| TyParam(_) | |
| TyInfer(_) | |
| TyError => { |
| vec![] |
| } |
| } |
| } |
| } |