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// 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 hir::def_id::DefId;
use middle::const_val::ConstVal;
use middle::region;
use rustc_data_structures::indexed_vec::Idx;
use ty::subst::{Substs, Subst};
use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
use ty::{Slice, TyS};
use ty::subst::Kind;
use std::iter;
use std::cmp::Ordering;
use syntax::abi;
use syntax::ast::{self, Name};
use syntax::symbol::keywords;
use serialize;
use hir;
use self::InferTy::*;
use self::TypeVariants::*;
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
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: DefId,
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),
/// Fresh bound identifiers created during GLB computations.
BrFresh(u32),
/// 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,
}
}
}
/// 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, RustcEncodable, RustcDecodable)]
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),
/// Structures, enumerations and unions.
///
/// 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 `TyAdt` corresponds to an ADT
/// definition and not a concrete use of it.
TyAdt(&'tcx AdtDef, &'tcx Substs<'tcx>),
TyForeign(DefId),
/// The pointee of a string slice. Written as `str`.
TyStr,
/// An array with the given length. Written as `[T; n]`.
TyArray(Ty<'tcx>, &'tcx ty::Const<'tcx>),
/// 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(Region<'tcx>, TypeAndMut<'tcx>),
/// The anonymous type of a function declaration/definition. Each
/// function has a unique type.
TyFnDef(DefId, &'tcx Substs<'tcx>),
/// A pointer to a function. Written as `fn() -> i32`.
TyFnPtr(PolyFnSig<'tcx>),
/// A trait, defined with `trait`.
TyDynamic(Binder<&'tcx Slice<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
/// The anonymous type of a closure. Used to represent the type of
/// `|a| a`.
TyClosure(DefId, ClosureSubsts<'tcx>),
/// The anonymous type of a generator. Used to represent the type of
/// `|a| yield a`.
TyGenerator(DefId, ClosureSubsts<'tcx>, GeneratorInterior<'tcx>),
/// The never type `!`
TyNever,
/// A tuple type. For example, `(i32, bool)`.
/// The bool indicates whether this is a unit tuple and was created by
/// defaulting a diverging type variable with feature(never_type) disabled.
/// It's only purpose is for raising future-compatibility warnings for when
/// diverging type variables start defaulting to ! instead of ().
TyTuple(&'tcx Slice<Ty<'tcx>>, bool),
/// The projection of an associated type. For example,
/// `<T as Trait<..>>::N`.
TyProjection(ProjectionTy<'tcx>),
/// Anonymized (`impl Trait`) type found in a return type.
/// The DefId comes from the `impl Trait` ast::Ty node, and the
/// substitutions are for the generics of the function in question.
/// After typeck, the concrete type can be found in the `types` map.
TyAnon(DefId, &'tcx Substs<'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, 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 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
///
/// ## Generators
///
/// Perhaps surprisingly, `ClosureSubsts` are also used for
/// generators. In that case, what is written above is only half-true
/// -- 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.
///
/// It'd be nice to split this struct into ClosureSubsts and
/// GeneratorSubsts, I believe. -nmatsakis
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct ClosureSubsts<'tcx> {
/// Lifetime and type parameters from the enclosing function,
/// concatenated with the types of the upvars.
///
/// These are separated out because trans wants to pass them around
/// when monomorphizing.
pub substs: &'tcx Substs<'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[parent_len].as_type().expect("CK should be a type"),
closure_sig_ty: self.substs[parent_len + 1].as_type().expect("CS should be a type"),
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| t.as_type().expect("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 type representing the yield type of the generator.
pub fn generator_yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
self.closure_kind_ty(def_id, tcx)
}
/// Returns the type representing the return type of the generator.
pub fn generator_return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
self.closure_sig_ty(def_id, tcx)
}
/// Return the "generator signature", which consists of its yield
/// and return types.
///
/// NB. 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 generator_poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
ty::Binder(self.generator_sig(def_id, tcx))
}
/// Return the "generator signature", which consists of its yield
/// and return types.
pub fn generator_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
ty::GenSig {
yield_ty: self.generator_yield_ty(def_id, tcx),
return_ty: self.generator_return_ty(def_id, tcx),
}
}
}
impl<'tcx> ClosureSubsts<'tcx> {
/// 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, '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, 'tcx>) -> ty::PolyFnSig<'tcx> {
match self.closure_sig_ty(def_id, tcx).sty {
ty::TyFnPtr(sig) => sig,
ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
}
}
}
impl<'a, 'gcx, 'tcx> ClosureSubsts<'tcx> {
/// 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.
pub fn state_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
impl Iterator<Item=Ty<'tcx>> + 'a
{
let state = tcx.generator_layout(def_id).fields.iter();
state.map(move |d| d.ty.subst(tcx, self.substs))
}
/// This is the types of all the fields stored in a generator.
/// It includes the upvars, state types and the state discriminant which is u32.
pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
impl Iterator<Item=Ty<'tcx>> + 'a
{
let upvars = self.upvar_tys(def_id, tcx);
let state = self.state_tys(def_id, tcx);
upvars.chain(iter::once(tcx.types.u32)).chain(state)
}
}
/// 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.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct GeneratorInterior<'tcx> {
pub witness: Ty<'tcx>,
}
impl<'tcx> GeneratorInterior<'tcx> {
pub fn new(witness: Ty<'tcx>) -> GeneratorInterior<'tcx> {
GeneratorInterior { witness }
}
pub fn as_slice(&self) -> &'tcx Slice<Ty<'tcx>> {
match self.witness.sty {
ty::TyTuple(s, _) => s,
_ => bug!(),
}
}
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub enum ExistentialPredicate<'tcx> {
/// e.g. Iterator
Trait(ExistentialTraitRef<'tcx>),
/// e.g. Iterator::Item = T
Projection(ExistentialProjection<'tcx>),
/// e.g. Send
AutoTrait(DefId),
}
impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
pub fn cmp(&self, tcx: TyCtxt<'a, 'gcx, '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<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
-> ty::Predicate<'tcx> {
use 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> serialize::UseSpecializedDecodable for &'tcx Slice<ExistentialPredicate<'tcx>> {}
impl<'tcx> Slice<ExistentialPredicate<'tcx>> {
pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
match self.get(0) {
Some(&ExistentialPredicate::Trait(tr)) => Some(tr),
_ => None,
}
}
#[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 Slice<ExistentialPredicate<'tcx>>> {
pub fn principal(&self) -> Option<PolyExistentialTraitRef<'tcx>> {
self.skip_binder().principal().map(Binder)
}
#[inline]
pub fn projection_bounds<'a>(&'a self) ->
impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
self.skip_binder().projection_bounds().map(Binder)
}
#[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)
}
}
/// 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 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)]
pub struct TraitRef<'tcx> {
pub def_id: DefId,
pub substs: &'tcx Substs<'tcx>,
}
impl<'tcx> TraitRef<'tcx> {
pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
TraitRef { def_id: def_id, substs: substs }
}
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 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<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
// 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() })
}
}
/// 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, Hash, RustcEncodable, RustcDecodable)]
pub struct ExistentialTraitRef<'tcx> {
pub def_id: DefId,
pub substs: &'tcx Substs<'tcx>,
}
impl<'a, 'gcx, '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()
}
/// 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 with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
-> ty::TraitRef<'tcx> {
// otherwise the escaping regions would be captured by the binder
assert!(!self_ty.has_escaping_regions());
ty::TraitRef {
def_id: self.def_id,
substs: tcx.mk_substs(
iter::once(Kind::from(self_ty)).chain(self.substs.iter().cloned()))
}
}
}
pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
impl<'tcx> PolyExistentialTraitRef<'tcx> {
pub fn def_id(&self) -> DefId {
self.0.def_id
}
pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
// FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
self.0.input_types()
}
}
/// 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, RustcEncodable, RustcDecodable)]
pub struct Binder<T>(pub T);
impl<T> Binder<T> {
/// Wraps `value` in a binder, asserting that `value` does not
/// contain any bound regions 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>
{
assert!(!value.has_escaping_regions());
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
/// 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))
}
/// Unwraps and returns the value within, but only if it contains
/// no bound regions 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 regions 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_late_bound_regions<'tcx>(self) -> Option<T>
where T : TypeFoldable<'tcx>
{
if self.skip_binder().has_escaping_regions() {
None
} else {
Some(self.skip_binder().clone())
}
}
/// Given two things that have the same binder level,
/// and an operation that wraps on their contents, execute the operation
/// and then wrap 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
{
ty::Binder(f(self.0, u.0))
}
/// Split 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);
(ty::Binder(u), ty::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, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct ProjectionTy<'tcx> {
/// The parameters of the associated item.
pub substs: &'tcx Substs<'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<'a, '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: Name
) -> ProjectionTy<'tcx> {
let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
item.kind == ty::AssociatedKind::Type &&
tcx.hygienic_eq(item_name, item.name, 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)]
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 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(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct FnSig<'tcx> {
pub inputs_and_output: &'tcx Slice<Ty<'tcx>>,
pub 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]
}
}
pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
impl<'tcx> PolyFnSig<'tcx> {
pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
Binder(self.skip_binder().inputs())
}
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 Slice<Ty<'tcx>>> {
self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
}
pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
self.map_bound_ref(|fn_sig| fn_sig.output().clone())
}
pub fn variadic(&self) -> bool {
self.skip_binder().variadic
}
pub fn unsafety(&self) -> hir::Unsafety {
self.skip_binder().unsafety
}
pub fn abi(&self) -> abi::Abi {
self.skip_binder().abi
}
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct ParamTy {
pub idx: u32,
pub name: Name,
}
impl<'a, 'gcx, 'tcx> ParamTy {
pub fn new(index: u32, name: Name) -> ParamTy {
ParamTy { idx: index, name: name }
}
pub fn for_self() -> ParamTy {
ParamTy::new(0, keywords::SelfType.name())
}
pub fn for_def(def: &ty::TypeParameterDef) -> ParamTy {
ParamTy::new(def.index, def.name)
}
pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
tcx.mk_param(self.idx, self.name)
}
pub fn is_self(&self) -> bool {
if self.name == keywords::SelfType.name() {
assert_eq!(self.idx, 0);
true
} else {
false
}
}
}
/// 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, PartialOrd, Ord)]
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,
}
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 2 kind of
/// bound regions: early-bound, which are bound in an item's Generics,
/// 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 explicitly 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, 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 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,
/// 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> 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: Name,
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct TyVid {
pub index: u32,
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct IntVid {
pub index: u32,
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct FloatVid {
pub index: u32,
}
newtype_index!(RegionVid
{
pub idx
DEBUG_FORMAT = custom,
});
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
pub struct SkolemizedRegionVid {
pub index: u32,
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
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),
}
/// A `ProjectionPredicate` for an `ExistentialTraitRef`.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct ExistentialProjection<'tcx> {
pub item_def_id: DefId,
pub substs: &'tcx Substs<'tcx>,
pub ty: Ty<'tcx>,
}
pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
impl<'a, 'tcx, 'gcx> 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<'a, 'gcx, 'tcx>,
self_ty: Ty<'tcx>)
-> ty::ProjectionPredicate<'tcx>
{
// otherwise the escaping regions would be captured by the binders
assert!(!self_ty.has_escaping_regions());
ty::ProjectionPredicate {
projection_ty: ty::ProjectionTy {
item_def_id: self.item_def_id,
substs: tcx.mk_substs(
iter::once(Kind::from(self_ty)).chain(self.substs.iter().cloned())),
},
ty: self.ty,
}
}
}
impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
-> ty::PolyProjectionPredicate<'tcx> {
self.map_bound(|p| p.with_self_ty(tcx, self_ty))
}
}
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 RegionKind {
pub fn is_late_bound(&self) -> bool {
match *self {
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) -> RegionKind {
match *self {
ty::ReLateBound(debruijn, r) => ty::ReLateBound(DebruijnIndex {
depth: debruijn.depth - (depth - 1)
}, r),
r => r
}
}
pub fn type_flags(&self) -> TypeFlags {
let mut flags = TypeFlags::empty();
match *self {
ty::ReVar(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_RE_INFER;
flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
}
ty::ReSkolemized(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_RE_INFER;
flags = flags | TypeFlags::HAS_RE_SKOL;
flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
}
ty::ReLateBound(..) => { }
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 => (),
_ => flags = flags | TypeFlags::HAS_LOCAL_NAMES,
}
debug!("type_flags({:?}) = {:?}", self, flags);
flags
}
/// Given an early-bound or free region, returns the def-id 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 def-id
/// of the impl, and for all the other highlighted regions, it
/// would return the def-id of the function. In other cases (not shown), this
/// function might return the def-id of a closure.
pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
match self {
ty::ReEarlyBound(br) => {
tcx.parent_def_id(br.def_id).unwrap()
}
ty::ReFree(fr) => fr.scope,
_ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
}
}
}
/// Type utilities
impl<'a, 'gcx, 'tcx> TyS<'tcx> {
pub fn is_nil(&self) -> bool {
match self.sty {
TyTuple(ref tys, _) => tys.is_empty(),
_ => false,
}
}
pub fn is_never(&self) -> bool {
match self.sty {
TyNever => true,
_ => false,
}
}
/// Test whether this is a `()` which was produced by defaulting a
/// diverging type variable with feature(never_type) disabled.
pub fn is_defaulted_unit(&self) -> bool {
match self.sty {
TyTuple(_, true) => true,
_ => 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 TyAdt(def, _) = self.sty {
def.is_phantom_data()
} else {
false
}
}
pub fn is_bool(&self) -> bool { self.sty == TyBool }
pub fn is_param(&self, index: u32) -> bool {
match self.sty {
ty::TyParam(ref data) => data.idx == index,
_ => false,
}
}
pub fn is_self(&self) -> bool {
match self.sty {
TyParam(ref p) => p.is_self(),
_ => false,
}
}
pub fn is_slice(&self) -> bool {
match self.sty {
TyRawPtr(mt) | TyRef(_, mt) => match mt.ty.sty {
TySlice(_) | TyStr => true,
_ => false,
},
_ => false
}
}
#[inline]
pub fn is_simd(&self) -> bool {
match self.sty {
TyAdt(def, _) => def.repr.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 {
TyAdt(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 {
TyAdt(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_mutable_pointer(&self) -> bool {
match self.sty {
TyRawPtr(tnm) | TyRef(_, tnm) => if let hir::Mutability::MutMutable = tnm.mutbl {
true
} else {
false
},
_ => false
}
}
pub fn is_unsafe_ptr(&self) -> bool {
match self.sty {
TyRawPtr(_) => return true,
_ => return false,
}
}
pub fn is_box(&self) -> bool {
match self.sty {
TyAdt(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 {
TyAdt(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 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 {
TyDynamic(..) => true,
_ => false,
}
}
pub fn is_enum(&self) -> bool {
match self.sty {
TyAdt(adt_def, _) => {
adt_def.is_enum()
}
_ => false,
}
}
pub fn is_closure(&self) -> bool {
match self.sty {
TyClosure(..) => true,
_ => false,
}
}
pub fn is_generator(&self) -> bool {
match self.sty {
TyGenerator(..) => true,
_ => false,
}
}
pub fn is_integral(&self) -> bool {
match self.sty {
TyInfer(IntVar(_)) | TyInt(_) | TyUint(_) => true,
_ => false
}
}
pub fn is_fresh_ty(&self) -> bool {
match self.sty {
TyInfer(FreshTy(_)) => true,
_ => false,
}
}
pub fn is_fresh(&self) -> bool {
match self.sty {
TyInfer(FreshTy(_)) => true,
TyInfer(FreshIntTy(_)) => true,
TyInfer(FreshFloatTy(_)) => 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::Isize) | TyUint(ast::UintTy::Usize) => 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 {
TyAdt(def, _) if def.is_box() => {
Some(TypeAndMut {
ty: self.boxed_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: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
match self.sty {
TyFnDef(def_id, substs) => {
tcx.fn_sig(def_id).subst(tcx, substs)
}
TyFnPtr(f) => f,
_ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
}
}
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 {
TyDynamic(ref tt, ..) => tt.principal().map(|p| p.def_id()),
TyAdt(def, _) => Some(def.did),
TyForeign(did) => Some(did),
TyClosure(id, _) => Some(id),
TyFnDef(id, _) => Some(id),
_ => None,
}
}
pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
match self.sty {
TyAdt(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<'tcx>> {
match self.sty {
TyRef(region, _) => {
vec![region]
}
TyDynamic(ref obj, region) => {
let mut v = vec![region];
if let Some(p) = obj.principal() {
v.extend(p.skip_binder().substs.regions());
}
v
}
TyAdt(_, substs) | TyAnon(_, substs) => {
substs.regions().collect()
}
TyClosure(_, ref substs) | TyGenerator(_, ref substs, _) => {
substs.substs.regions().collect()
}
TyProjection(ref data) => {
data.substs.regions().collect()
}
TyFnDef(..) |
TyFnPtr(_) |
TyBool |
TyChar |
TyInt(_) |
TyUint(_) |
TyFloat(_) |
TyStr |
TyArray(..) |
TySlice(_) |
TyRawPtr(_) |
TyNever |
TyTuple(..) |
TyForeign(..) |
TyParam(_) |
TyInfer(_) |
TyError => {
vec![]
}
}
}
/// 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 {
TyInt(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),
},
TyInfer(_) => None,
TyError => Some(ty::ClosureKind::Fn),
_ => bug!("cannot convert type `{:?}` to a closure kind", self),
}
}
}
/// Typed constant value.
#[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq)]
pub struct Const<'tcx> {
pub ty: Ty<'tcx>,
// FIXME(eddyb) Replace this with a miri value.
pub val: ConstVal<'tcx>,
}
impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}
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