| // 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. |
| |
| //! misc. type-system utilities too small to deserve their own file |
| |
| use hir::svh::Svh; |
| use hir::def_id::DefId; |
| use ty::subst; |
| use infer::InferCtxt; |
| use hir::pat_util; |
| use traits::{self, ProjectionMode}; |
| use ty::{self, Ty, TyCtxt, TypeAndMut, TypeFlags, TypeFoldable}; |
| use ty::{Disr, ParameterEnvironment}; |
| use ty::layout::{Layout, LayoutError}; |
| use ty::TypeVariants::*; |
| |
| use rustc_const_math::{ConstInt, ConstIsize, ConstUsize}; |
| |
| use std::cmp; |
| use std::hash::{Hash, SipHasher, Hasher}; |
| use syntax::ast::{self, Name}; |
| use syntax::attr::{self, SignedInt, UnsignedInt}; |
| use syntax_pos::Span; |
| |
| use hir; |
| |
| pub trait IntTypeExt { |
| fn to_ty<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Ty<'tcx>; |
| fn disr_incr<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, val: Option<Disr>) |
| -> Option<Disr>; |
| fn assert_ty_matches(&self, val: Disr); |
| fn initial_discriminant<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Disr; |
| } |
| |
| impl IntTypeExt for attr::IntType { |
| fn to_ty<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Ty<'tcx> { |
| match *self { |
| SignedInt(ast::IntTy::I8) => tcx.types.i8, |
| SignedInt(ast::IntTy::I16) => tcx.types.i16, |
| SignedInt(ast::IntTy::I32) => tcx.types.i32, |
| SignedInt(ast::IntTy::I64) => tcx.types.i64, |
| SignedInt(ast::IntTy::Is) => tcx.types.isize, |
| UnsignedInt(ast::UintTy::U8) => tcx.types.u8, |
| UnsignedInt(ast::UintTy::U16) => tcx.types.u16, |
| UnsignedInt(ast::UintTy::U32) => tcx.types.u32, |
| UnsignedInt(ast::UintTy::U64) => tcx.types.u64, |
| UnsignedInt(ast::UintTy::Us) => tcx.types.usize, |
| } |
| } |
| |
| fn initial_discriminant<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Disr { |
| match *self { |
| SignedInt(ast::IntTy::I8) => ConstInt::I8(0), |
| SignedInt(ast::IntTy::I16) => ConstInt::I16(0), |
| SignedInt(ast::IntTy::I32) => ConstInt::I32(0), |
| SignedInt(ast::IntTy::I64) => ConstInt::I64(0), |
| SignedInt(ast::IntTy::Is) => match tcx.sess.target.int_type { |
| ast::IntTy::I16 => ConstInt::Isize(ConstIsize::Is16(0)), |
| ast::IntTy::I32 => ConstInt::Isize(ConstIsize::Is32(0)), |
| ast::IntTy::I64 => ConstInt::Isize(ConstIsize::Is64(0)), |
| _ => bug!(), |
| }, |
| UnsignedInt(ast::UintTy::U8) => ConstInt::U8(0), |
| UnsignedInt(ast::UintTy::U16) => ConstInt::U16(0), |
| UnsignedInt(ast::UintTy::U32) => ConstInt::U32(0), |
| UnsignedInt(ast::UintTy::U64) => ConstInt::U64(0), |
| UnsignedInt(ast::UintTy::Us) => match tcx.sess.target.uint_type { |
| ast::UintTy::U16 => ConstInt::Usize(ConstUsize::Us16(0)), |
| ast::UintTy::U32 => ConstInt::Usize(ConstUsize::Us32(0)), |
| ast::UintTy::U64 => ConstInt::Usize(ConstUsize::Us64(0)), |
| _ => bug!(), |
| }, |
| } |
| } |
| |
| fn assert_ty_matches(&self, val: Disr) { |
| match (*self, val) { |
| (SignedInt(ast::IntTy::I8), ConstInt::I8(_)) => {}, |
| (SignedInt(ast::IntTy::I16), ConstInt::I16(_)) => {}, |
| (SignedInt(ast::IntTy::I32), ConstInt::I32(_)) => {}, |
| (SignedInt(ast::IntTy::I64), ConstInt::I64(_)) => {}, |
| (SignedInt(ast::IntTy::Is), ConstInt::Isize(_)) => {}, |
| (UnsignedInt(ast::UintTy::U8), ConstInt::U8(_)) => {}, |
| (UnsignedInt(ast::UintTy::U16), ConstInt::U16(_)) => {}, |
| (UnsignedInt(ast::UintTy::U32), ConstInt::U32(_)) => {}, |
| (UnsignedInt(ast::UintTy::U64), ConstInt::U64(_)) => {}, |
| (UnsignedInt(ast::UintTy::Us), ConstInt::Usize(_)) => {}, |
| _ => bug!("disr type mismatch: {:?} vs {:?}", self, val), |
| } |
| } |
| |
| fn disr_incr<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, val: Option<Disr>) |
| -> Option<Disr> { |
| if let Some(val) = val { |
| self.assert_ty_matches(val); |
| (val + ConstInt::Infer(1)).ok() |
| } else { |
| Some(self.initial_discriminant(tcx)) |
| } |
| } |
| } |
| |
| |
| #[derive(Copy, Clone)] |
| pub enum CopyImplementationError { |
| InfrigingField(Name), |
| InfrigingVariant(Name), |
| NotAnAdt, |
| HasDestructor |
| } |
| |
| /// Describes whether a type is representable. For types that are not |
| /// representable, 'SelfRecursive' and 'ContainsRecursive' are used to |
| /// distinguish between types that are recursive with themselves and types that |
| /// contain a different recursive type. These cases can therefore be treated |
| /// differently when reporting errors. |
| /// |
| /// The ordering of the cases is significant. They are sorted so that cmp::max |
| /// will keep the "more erroneous" of two values. |
| #[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Debug)] |
| pub enum Representability { |
| Representable, |
| ContainsRecursive, |
| SelfRecursive, |
| } |
| |
| impl<'tcx> ParameterEnvironment<'tcx> { |
| pub fn can_type_implement_copy<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| self_type: Ty<'tcx>, span: Span) |
| -> Result<(),CopyImplementationError> { |
| // FIXME: (@jroesch) float this code up |
| tcx.infer_ctxt(None, Some(self.clone()), |
| ProjectionMode::Topmost).enter(|infcx| { |
| let adt = match self_type.sty { |
| ty::TyStruct(struct_def, substs) => { |
| for field in struct_def.all_fields() { |
| let field_ty = field.ty(tcx, substs); |
| if infcx.type_moves_by_default(field_ty, span) { |
| return Err(CopyImplementationError::InfrigingField( |
| field.name)) |
| } |
| } |
| struct_def |
| } |
| ty::TyEnum(enum_def, substs) => { |
| for variant in &enum_def.variants { |
| for field in &variant.fields { |
| let field_ty = field.ty(tcx, substs); |
| if infcx.type_moves_by_default(field_ty, span) { |
| return Err(CopyImplementationError::InfrigingVariant( |
| variant.name)) |
| } |
| } |
| } |
| enum_def |
| } |
| _ => return Err(CopyImplementationError::NotAnAdt) |
| }; |
| |
| if adt.has_dtor() { |
| return Err(CopyImplementationError::HasDestructor); |
| } |
| |
| Ok(()) |
| }) |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { |
| pub fn pat_contains_ref_binding(self, pat: &hir::Pat) -> Option<hir::Mutability> { |
| pat_util::pat_contains_ref_binding(pat) |
| } |
| |
| pub fn arm_contains_ref_binding(self, arm: &hir::Arm) -> Option<hir::Mutability> { |
| pat_util::arm_contains_ref_binding(arm) |
| } |
| |
| pub fn has_error_field(self, ty: Ty<'tcx>) -> bool { |
| match ty.sty { |
| ty::TyStruct(def, substs) | ty::TyEnum(def, substs) => { |
| for field in def.all_fields() { |
| let field_ty = field.ty(self, substs); |
| if let TyError = field_ty.sty { |
| return true; |
| } |
| } |
| } |
| _ => () |
| } |
| false |
| } |
| |
| /// Returns the type of element at index `i` in tuple or tuple-like type `t`. |
| /// For an enum `t`, `variant` is None only if `t` is a univariant enum. |
| pub fn positional_element_ty(self, |
| ty: Ty<'tcx>, |
| i: usize, |
| variant: Option<DefId>) -> Option<Ty<'tcx>> { |
| match (&ty.sty, variant) { |
| (&TyStruct(def, substs), None) => { |
| def.struct_variant().fields.get(i).map(|f| f.ty(self, substs)) |
| } |
| (&TyEnum(def, substs), Some(vid)) => { |
| def.variant_with_id(vid).fields.get(i).map(|f| f.ty(self, substs)) |
| } |
| (&TyEnum(def, substs), None) => { |
| assert!(def.is_univariant()); |
| def.variants[0].fields.get(i).map(|f| f.ty(self, substs)) |
| } |
| (&TyTuple(ref v), None) => v.get(i).cloned(), |
| _ => None |
| } |
| } |
| |
| /// Returns the type of element at field `n` in struct or struct-like type `t`. |
| /// For an enum `t`, `variant` must be some def id. |
| pub fn named_element_ty(self, |
| ty: Ty<'tcx>, |
| n: Name, |
| variant: Option<DefId>) -> Option<Ty<'tcx>> { |
| match (&ty.sty, variant) { |
| (&TyStruct(def, substs), None) => { |
| def.struct_variant().find_field_named(n).map(|f| f.ty(self, substs)) |
| } |
| (&TyEnum(def, substs), Some(vid)) => { |
| def.variant_with_id(vid).find_field_named(n).map(|f| f.ty(self, substs)) |
| } |
| _ => return None |
| } |
| } |
| |
| /// Returns the IntType representation. |
| /// This used to ensure `int_ty` doesn't contain `usize` and `isize` |
| /// by converting them to their actual types. That doesn't happen anymore. |
| pub fn enum_repr_type(self, opt_hint: Option<&attr::ReprAttr>) -> attr::IntType { |
| match opt_hint { |
| // Feed in the given type |
| Some(&attr::ReprInt(_, int_t)) => int_t, |
| // ... but provide sensible default if none provided |
| // |
| // NB. Historically `fn enum_variants` generate i64 here, while |
| // rustc_typeck::check would generate isize. |
| _ => SignedInt(ast::IntTy::Is), |
| } |
| } |
| |
| /// Returns the deeply last field of nested structures, or the same type, |
| /// if not a structure at all. Corresponds to the only possible unsized |
| /// field, and its type can be used to determine unsizing strategy. |
| pub fn struct_tail(self, mut ty: Ty<'tcx>) -> Ty<'tcx> { |
| while let TyStruct(def, substs) = ty.sty { |
| match def.struct_variant().fields.last() { |
| Some(f) => ty = f.ty(self, substs), |
| None => break |
| } |
| } |
| ty |
| } |
| |
| /// Same as applying struct_tail on `source` and `target`, but only |
| /// keeps going as long as the two types are instances of the same |
| /// structure definitions. |
| /// For `(Foo<Foo<T>>, Foo<Trait>)`, the result will be `(Foo<T>, Trait)`, |
| /// whereas struct_tail produces `T`, and `Trait`, respectively. |
| pub fn struct_lockstep_tails(self, |
| source: Ty<'tcx>, |
| target: Ty<'tcx>) |
| -> (Ty<'tcx>, Ty<'tcx>) { |
| let (mut a, mut b) = (source, target); |
| while let (&TyStruct(a_def, a_substs), &TyStruct(b_def, b_substs)) = (&a.sty, &b.sty) { |
| if a_def != b_def { |
| break; |
| } |
| if let Some(f) = a_def.struct_variant().fields.last() { |
| a = f.ty(self, a_substs); |
| b = f.ty(self, b_substs); |
| } else { |
| break; |
| } |
| } |
| (a, b) |
| } |
| |
| /// Given a set of predicates that apply to an object type, returns |
| /// the region bounds that the (erased) `Self` type must |
| /// outlive. Precisely *because* the `Self` type is erased, the |
| /// parameter `erased_self_ty` must be supplied to indicate what type |
| /// has been used to represent `Self` in the predicates |
| /// themselves. This should really be a unique type; `FreshTy(0)` is a |
| /// popular choice. |
| /// |
| /// NB: in some cases, particularly around higher-ranked bounds, |
| /// this function returns a kind of conservative approximation. |
| /// That is, all regions returned by this function are definitely |
| /// required, but there may be other region bounds that are not |
| /// returned, as well as requirements like `for<'a> T: 'a`. |
| /// |
| /// Requires that trait definitions have been processed so that we can |
| /// elaborate predicates and walk supertraits. |
| pub fn required_region_bounds(self, |
| erased_self_ty: Ty<'tcx>, |
| predicates: Vec<ty::Predicate<'tcx>>) |
| -> Vec<ty::Region> { |
| debug!("required_region_bounds(erased_self_ty={:?}, predicates={:?})", |
| erased_self_ty, |
| predicates); |
| |
| assert!(!erased_self_ty.has_escaping_regions()); |
| |
| traits::elaborate_predicates(self, predicates) |
| .filter_map(|predicate| { |
| match predicate { |
| ty::Predicate::Projection(..) | |
| ty::Predicate::Trait(..) | |
| ty::Predicate::Rfc1592(..) | |
| ty::Predicate::Equate(..) | |
| ty::Predicate::WellFormed(..) | |
| ty::Predicate::ObjectSafe(..) | |
| ty::Predicate::ClosureKind(..) | |
| ty::Predicate::RegionOutlives(..) => { |
| None |
| } |
| ty::Predicate::TypeOutlives(ty::Binder(ty::OutlivesPredicate(t, r))) => { |
| // Search for a bound of the form `erased_self_ty |
| // : 'a`, but be wary of something like `for<'a> |
| // erased_self_ty : 'a` (we interpret a |
| // higher-ranked bound like that as 'static, |
| // though at present the code in `fulfill.rs` |
| // considers such bounds to be unsatisfiable, so |
| // it's kind of a moot point since you could never |
| // construct such an object, but this seems |
| // correct even if that code changes). |
| if t == erased_self_ty && !r.has_escaping_regions() { |
| Some(r) |
| } else { |
| None |
| } |
| } |
| } |
| }) |
| .collect() |
| } |
| |
| /// Creates a hash of the type `Ty` which will be the same no matter what crate |
| /// context it's calculated within. This is used by the `type_id` intrinsic. |
| pub fn hash_crate_independent(self, ty: Ty<'tcx>, svh: &Svh) -> u64 { |
| let mut state = SipHasher::new(); |
| helper(self, ty, svh, &mut state); |
| return state.finish(); |
| |
| fn helper<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, |
| ty: Ty<'tcx>, svh: &Svh, |
| state: &mut SipHasher) { |
| macro_rules! byte { ($b:expr) => { ($b as u8).hash(state) } } |
| macro_rules! hash { ($e:expr) => { $e.hash(state) } } |
| |
| let region = |state: &mut SipHasher, r: ty::Region| { |
| match r { |
| ty::ReStatic | ty::ReErased => {} |
| ty::ReLateBound(db, ty::BrAnon(i)) => { |
| db.hash(state); |
| i.hash(state); |
| } |
| ty::ReEmpty | |
| ty::ReEarlyBound(..) | |
| ty::ReLateBound(..) | |
| ty::ReFree(..) | |
| ty::ReScope(..) | |
| ty::ReVar(..) | |
| ty::ReSkolemized(..) => { |
| bug!("unexpected region found when hashing a type") |
| } |
| } |
| }; |
| let did = |state: &mut SipHasher, did: DefId| { |
| let h = if did.is_local() { |
| svh.clone() |
| } else { |
| tcx.sess.cstore.crate_hash(did.krate) |
| }; |
| h.hash(state); |
| did.index.hash(state); |
| }; |
| let mt = |state: &mut SipHasher, mt: TypeAndMut| { |
| mt.mutbl.hash(state); |
| }; |
| let fn_sig = |state: &mut SipHasher, sig: &ty::Binder<ty::FnSig<'tcx>>| { |
| let sig = tcx.anonymize_late_bound_regions(sig).0; |
| for a in &sig.inputs { helper(tcx, *a, svh, state); } |
| if let ty::FnConverging(output) = sig.output { |
| helper(tcx, output, svh, state); |
| } |
| }; |
| ty.maybe_walk(|ty| { |
| match ty.sty { |
| TyBool => byte!(2), |
| TyChar => byte!(3), |
| TyInt(i) => { |
| byte!(4); |
| hash!(i); |
| } |
| TyUint(u) => { |
| byte!(5); |
| hash!(u); |
| } |
| TyFloat(f) => { |
| byte!(6); |
| hash!(f); |
| } |
| TyStr => { |
| byte!(7); |
| } |
| TyEnum(d, _) => { |
| byte!(8); |
| did(state, d.did); |
| } |
| TyBox(_) => { |
| byte!(9); |
| } |
| TyArray(_, n) => { |
| byte!(10); |
| n.hash(state); |
| } |
| TySlice(_) => { |
| byte!(11); |
| } |
| TyRawPtr(m) => { |
| byte!(12); |
| mt(state, m); |
| } |
| TyRef(r, m) => { |
| byte!(13); |
| region(state, *r); |
| mt(state, m); |
| } |
| TyFnDef(def_id, _, _) => { |
| byte!(14); |
| hash!(def_id); |
| } |
| TyFnPtr(ref b) => { |
| byte!(15); |
| hash!(b.unsafety); |
| hash!(b.abi); |
| fn_sig(state, &b.sig); |
| return false; |
| } |
| TyTrait(ref data) => { |
| byte!(17); |
| did(state, data.principal_def_id()); |
| hash!(data.bounds); |
| |
| let principal = tcx.anonymize_late_bound_regions(&data.principal).0; |
| for subty in &principal.substs.types { |
| helper(tcx, subty, svh, state); |
| } |
| |
| return false; |
| } |
| TyStruct(d, _) => { |
| byte!(18); |
| did(state, d.did); |
| } |
| TyTuple(ref inner) => { |
| byte!(19); |
| hash!(inner.len()); |
| } |
| TyParam(p) => { |
| byte!(20); |
| hash!(p.space); |
| hash!(p.idx); |
| hash!(p.name.as_str()); |
| } |
| TyInfer(_) => bug!(), |
| TyError => byte!(21), |
| TyClosure(d, _) => { |
| byte!(22); |
| did(state, d); |
| } |
| TyProjection(ref data) => { |
| byte!(23); |
| did(state, data.trait_ref.def_id); |
| hash!(data.item_name.as_str()); |
| } |
| } |
| true |
| }); |
| } |
| } |
| |
| /// Returns true if this ADT is a dtorck type. |
| /// |
| /// Invoking the destructor of a dtorck type during usual cleanup |
| /// (e.g. the glue emitted for stack unwinding) requires all |
| /// lifetimes in the type-structure of `adt` to strictly outlive |
| /// the adt value itself. |
| /// |
| /// If `adt` is not dtorck, then the adt's destructor can be |
| /// invoked even when there are lifetimes in the type-structure of |
| /// `adt` that do not strictly outlive the adt value itself. |
| /// (This allows programs to make cyclic structures without |
| /// resorting to unasfe means; see RFCs 769 and 1238). |
| pub fn is_adt_dtorck(self, adt: ty::AdtDef) -> bool { |
| let dtor_method = match adt.destructor() { |
| Some(dtor) => dtor, |
| None => return false |
| }; |
| |
| // RFC 1238: if the destructor method is tagged with the |
| // attribute `unsafe_destructor_blind_to_params`, then the |
| // compiler is being instructed to *assume* that the |
| // destructor will not access borrowed data, |
| // even if such data is otherwise reachable. |
| // |
| // Such access can be in plain sight (e.g. dereferencing |
| // `*foo.0` of `Foo<'a>(&'a u32)`) or indirectly hidden |
| // (e.g. calling `foo.0.clone()` of `Foo<T:Clone>`). |
| return !self.has_attr(dtor_method, "unsafe_destructor_blind_to_params"); |
| } |
| } |
| |
| impl<'a, 'tcx> ty::TyS<'tcx> { |
| fn impls_bound(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| param_env: &ParameterEnvironment<'tcx>, |
| bound: ty::BuiltinBound, span: Span) -> bool |
| { |
| tcx.infer_ctxt(None, Some(param_env.clone()), ProjectionMode::Topmost).enter(|infcx| { |
| traits::type_known_to_meet_builtin_bound(&infcx, self, bound, span) |
| }) |
| } |
| |
| // FIXME (@jroesch): I made this public to use it, not sure if should be private |
| pub fn moves_by_default(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| param_env: &ParameterEnvironment<'tcx>, |
| span: Span) -> bool { |
| if self.flags.get().intersects(TypeFlags::MOVENESS_CACHED) { |
| return self.flags.get().intersects(TypeFlags::MOVES_BY_DEFAULT); |
| } |
| |
| assert!(!self.needs_infer()); |
| |
| // Fast-path for primitive types |
| let result = match self.sty { |
| TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) | |
| TyRawPtr(..) | TyFnDef(..) | TyFnPtr(_) | TyRef(_, TypeAndMut { |
| mutbl: hir::MutImmutable, .. |
| }) => Some(false), |
| |
| TyStr | TyBox(..) | TyRef(_, TypeAndMut { |
| mutbl: hir::MutMutable, .. |
| }) => Some(true), |
| |
| TyArray(..) | TySlice(_) | TyTrait(..) | TyTuple(..) | |
| TyClosure(..) | TyEnum(..) | TyStruct(..) | |
| TyProjection(..) | TyParam(..) | TyInfer(..) | TyError => None |
| }.unwrap_or_else(|| !self.impls_bound(tcx, param_env, ty::BoundCopy, span)); |
| |
| if !self.has_param_types() && !self.has_self_ty() { |
| self.flags.set(self.flags.get() | if result { |
| TypeFlags::MOVENESS_CACHED | TypeFlags::MOVES_BY_DEFAULT |
| } else { |
| TypeFlags::MOVENESS_CACHED |
| }); |
| } |
| |
| result |
| } |
| |
| #[inline] |
| pub fn is_sized(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| param_env: &ParameterEnvironment<'tcx>, |
| span: Span) -> bool |
| { |
| if self.flags.get().intersects(TypeFlags::SIZEDNESS_CACHED) { |
| return self.flags.get().intersects(TypeFlags::IS_SIZED); |
| } |
| |
| self.is_sized_uncached(tcx, param_env, span) |
| } |
| |
| fn is_sized_uncached(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| param_env: &ParameterEnvironment<'tcx>, |
| span: Span) -> bool { |
| assert!(!self.needs_infer()); |
| |
| // Fast-path for primitive types |
| let result = match self.sty { |
| TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) | |
| TyBox(..) | TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) | |
| TyArray(..) | TyTuple(..) | TyClosure(..) => Some(true), |
| |
| TyStr | TyTrait(..) | TySlice(_) => Some(false), |
| |
| TyEnum(..) | TyStruct(..) | TyProjection(..) | TyParam(..) | |
| TyInfer(..) | TyError => None |
| }.unwrap_or_else(|| self.impls_bound(tcx, param_env, ty::BoundSized, span)); |
| |
| if !self.has_param_types() && !self.has_self_ty() { |
| self.flags.set(self.flags.get() | if result { |
| TypeFlags::SIZEDNESS_CACHED | TypeFlags::IS_SIZED |
| } else { |
| TypeFlags::SIZEDNESS_CACHED |
| }); |
| } |
| |
| result |
| } |
| |
| #[inline] |
| pub fn layout<'lcx>(&'tcx self, infcx: &InferCtxt<'a, 'tcx, 'lcx>) |
| -> Result<&'tcx Layout, LayoutError<'tcx>> { |
| let tcx = infcx.tcx.global_tcx(); |
| let can_cache = !self.has_param_types() && !self.has_self_ty(); |
| if can_cache { |
| if let Some(&cached) = tcx.layout_cache.borrow().get(&self) { |
| return Ok(cached); |
| } |
| } |
| |
| let layout = Layout::compute_uncached(self, infcx)?; |
| let layout = tcx.intern_layout(layout); |
| if can_cache { |
| tcx.layout_cache.borrow_mut().insert(self, layout); |
| } |
| Ok(layout) |
| } |
| |
| |
| /// Check whether a type is representable. This means it cannot contain unboxed |
| /// structural recursion. This check is needed for structs and enums. |
| pub fn is_representable(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>, sp: Span) |
| -> Representability { |
| |
| // Iterate until something non-representable is found |
| fn find_nonrepresentable<'a, 'tcx, It>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| sp: Span, |
| seen: &mut Vec<Ty<'tcx>>, |
| iter: It) |
| -> Representability |
| where It: Iterator<Item=Ty<'tcx>> { |
| iter.fold(Representability::Representable, |
| |r, ty| cmp::max(r, is_type_structurally_recursive(tcx, sp, seen, ty))) |
| } |
| |
| fn are_inner_types_recursive<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, sp: Span, |
| seen: &mut Vec<Ty<'tcx>>, ty: Ty<'tcx>) |
| -> Representability { |
| match ty.sty { |
| TyTuple(ref ts) => { |
| find_nonrepresentable(tcx, sp, seen, ts.iter().cloned()) |
| } |
| // Fixed-length vectors. |
| // FIXME(#11924) Behavior undecided for zero-length vectors. |
| TyArray(ty, _) => { |
| is_type_structurally_recursive(tcx, sp, seen, ty) |
| } |
| TyStruct(def, substs) | TyEnum(def, substs) => { |
| find_nonrepresentable(tcx, |
| sp, |
| seen, |
| def.all_fields().map(|f| f.ty(tcx, substs))) |
| } |
| TyClosure(..) => { |
| // this check is run on type definitions, so we don't expect |
| // to see closure types |
| bug!("requires check invoked on inapplicable type: {:?}", ty) |
| } |
| _ => Representability::Representable, |
| } |
| } |
| |
| fn same_struct_or_enum<'tcx>(ty: Ty<'tcx>, def: ty::AdtDef<'tcx>) -> bool { |
| match ty.sty { |
| TyStruct(ty_def, _) | TyEnum(ty_def, _) => { |
| ty_def == def |
| } |
| _ => false |
| } |
| } |
| |
| fn same_type<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool { |
| match (&a.sty, &b.sty) { |
| (&TyStruct(did_a, ref substs_a), &TyStruct(did_b, ref substs_b)) | |
| (&TyEnum(did_a, ref substs_a), &TyEnum(did_b, ref substs_b)) => { |
| if did_a != did_b { |
| return false; |
| } |
| |
| let types_a = substs_a.types.get_slice(subst::TypeSpace); |
| let types_b = substs_b.types.get_slice(subst::TypeSpace); |
| |
| let mut pairs = types_a.iter().zip(types_b); |
| |
| pairs.all(|(&a, &b)| same_type(a, b)) |
| } |
| _ => { |
| a == b |
| } |
| } |
| } |
| |
| // Does the type `ty` directly (without indirection through a pointer) |
| // contain any types on stack `seen`? |
| fn is_type_structurally_recursive<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| sp: Span, |
| seen: &mut Vec<Ty<'tcx>>, |
| ty: Ty<'tcx>) -> Representability { |
| debug!("is_type_structurally_recursive: {:?}", ty); |
| |
| match ty.sty { |
| TyStruct(def, _) | TyEnum(def, _) => { |
| { |
| // Iterate through stack of previously seen types. |
| let mut iter = seen.iter(); |
| |
| // The first item in `seen` is the type we are actually curious about. |
| // We want to return SelfRecursive if this type contains itself. |
| // It is important that we DON'T take generic parameters into account |
| // for this check, so that Bar<T> in this example counts as SelfRecursive: |
| // |
| // struct Foo; |
| // struct Bar<T> { x: Bar<Foo> } |
| |
| if let Some(&seen_type) = iter.next() { |
| if same_struct_or_enum(seen_type, def) { |
| debug!("SelfRecursive: {:?} contains {:?}", |
| seen_type, |
| ty); |
| return Representability::SelfRecursive; |
| } |
| } |
| |
| // We also need to know whether the first item contains other types |
| // that are structurally recursive. If we don't catch this case, we |
| // will recurse infinitely for some inputs. |
| // |
| // It is important that we DO take generic parameters into account |
| // here, so that code like this is considered SelfRecursive, not |
| // ContainsRecursive: |
| // |
| // struct Foo { Option<Option<Foo>> } |
| |
| for &seen_type in iter { |
| if same_type(ty, seen_type) { |
| debug!("ContainsRecursive: {:?} contains {:?}", |
| seen_type, |
| ty); |
| return Representability::ContainsRecursive; |
| } |
| } |
| } |
| |
| // For structs and enums, track all previously seen types by pushing them |
| // onto the 'seen' stack. |
| seen.push(ty); |
| let out = are_inner_types_recursive(tcx, sp, seen, ty); |
| seen.pop(); |
| out |
| } |
| _ => { |
| // No need to push in other cases. |
| are_inner_types_recursive(tcx, sp, seen, ty) |
| } |
| } |
| } |
| |
| debug!("is_type_representable: {:?}", self); |
| |
| // To avoid a stack overflow when checking an enum variant or struct that |
| // contains a different, structurally recursive type, maintain a stack |
| // of seen types and check recursion for each of them (issues #3008, #3779). |
| let mut seen: Vec<Ty> = Vec::new(); |
| let r = is_type_structurally_recursive(tcx, sp, &mut seen, self); |
| debug!("is_type_representable: {:?} is {:?}", self, r); |
| r |
| } |
| } |
