| use crate::ty::subst::{GenericArgKind, SubstsRef}; |
| use crate::ty::{self, InferConst, Ty, TypeFlags}; |
| |
| #[derive(Debug)] |
| pub struct FlagComputation { |
| pub flags: TypeFlags, |
| |
| // see `TyS::outer_exclusive_binder` for details |
| pub outer_exclusive_binder: ty::DebruijnIndex, |
| } |
| |
| impl FlagComputation { |
| fn new() -> FlagComputation { |
| FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST } |
| } |
| |
| #[allow(rustc::usage_of_ty_tykind)] |
| pub fn for_kind(kind: &ty::TyKind<'_>) -> FlagComputation { |
| let mut result = FlagComputation::new(); |
| result.add_kind(kind); |
| result |
| } |
| |
| pub fn for_const(c: &ty::Const<'_>) -> TypeFlags { |
| let mut result = FlagComputation::new(); |
| result.add_const(c); |
| result.flags |
| } |
| |
| fn add_flags(&mut self, flags: TypeFlags) { |
| self.flags = self.flags | (flags & TypeFlags::NOMINAL_FLAGS); |
| } |
| |
| /// indicates that `self` refers to something at binding level `binder` |
| fn add_binder(&mut self, binder: ty::DebruijnIndex) { |
| let exclusive_binder = binder.shifted_in(1); |
| self.add_exclusive_binder(exclusive_binder); |
| } |
| |
| /// indicates that `self` refers to something *inside* binding |
| /// level `binder` -- not bound by `binder`, but bound by the next |
| /// binder internal to it |
| fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) { |
| self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder); |
| } |
| |
| /// Adds the flags/depth from a set of types that appear within the current type, but within a |
| /// region binder. |
| fn add_bound_computation(&mut self, computation: &FlagComputation) { |
| self.add_flags(computation.flags); |
| |
| // The types that contributed to `computation` occurred within |
| // a region binder, so subtract one from the region depth |
| // within when adding the depth to `self`. |
| let outer_exclusive_binder = computation.outer_exclusive_binder; |
| if outer_exclusive_binder > ty::INNERMOST { |
| self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1)); |
| } // otherwise, this binder captures nothing |
| } |
| |
| #[allow(rustc::usage_of_ty_tykind)] |
| fn add_kind(&mut self, kind: &ty::TyKind<'_>) { |
| match kind { |
| &ty::Bool |
| | &ty::Char |
| | &ty::Int(_) |
| | &ty::Float(_) |
| | &ty::Uint(_) |
| | &ty::Never |
| | &ty::Str |
| | &ty::Foreign(..) => {} |
| |
| // You might think that we could just return Error for |
| // any type containing Error as a component, and get |
| // rid of the TypeFlags::HAS_TY_ERR flag -- likewise for ty_bot (with |
| // the exception of function types that return bot). |
| // But doing so caused sporadic memory corruption, and |
| // neither I (tjc) nor nmatsakis could figure out why, |
| // so we're doing it this way. |
| &ty::Error => self.add_flags(TypeFlags::HAS_TY_ERR), |
| |
| &ty::Param(_) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_flags(TypeFlags::HAS_PARAMS); |
| } |
| |
| &ty::Generator(_, ref substs, _) => { |
| self.add_flags(TypeFlags::HAS_TY_CLOSURE); |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_substs(substs); |
| } |
| |
| &ty::GeneratorWitness(ref ts) => { |
| let mut computation = FlagComputation::new(); |
| computation.add_tys(&ts.skip_binder()[..]); |
| self.add_bound_computation(&computation); |
| } |
| |
| &ty::Closure(_, ref substs) => { |
| self.add_flags(TypeFlags::HAS_TY_CLOSURE); |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_substs(substs); |
| } |
| |
| &ty::Bound(debruijn, _) => { |
| self.add_binder(debruijn); |
| } |
| |
| &ty::Placeholder(..) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER); |
| } |
| |
| &ty::Infer(infer) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); // it might, right? |
| self.add_flags(TypeFlags::HAS_TY_INFER); |
| match infer { |
| ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {} |
| |
| ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => { |
| self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX) |
| } |
| } |
| } |
| |
| &ty::Adt(_, substs) => { |
| self.add_substs(substs); |
| } |
| |
| &ty::Projection(ref data) => { |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| self.add_projection_ty(data); |
| } |
| |
| &ty::UnnormalizedProjection(ref data) => { |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| self.add_projection_ty(data); |
| } |
| |
| &ty::Opaque(_, substs) => { |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| self.add_substs(substs); |
| } |
| |
| &ty::Dynamic(ref obj, r) => { |
| let mut computation = FlagComputation::new(); |
| for predicate in obj.skip_binder().iter() { |
| match *predicate { |
| ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs), |
| ty::ExistentialPredicate::Projection(p) => { |
| let mut proj_computation = FlagComputation::new(); |
| proj_computation.add_existential_projection(&p); |
| self.add_bound_computation(&proj_computation); |
| } |
| ty::ExistentialPredicate::AutoTrait(_) => {} |
| } |
| } |
| self.add_bound_computation(&computation); |
| self.add_region(r); |
| } |
| |
| &ty::Array(tt, len) => { |
| self.add_ty(tt); |
| self.add_const(len); |
| } |
| |
| &ty::Slice(tt) => self.add_ty(tt), |
| |
| &ty::RawPtr(ref m) => { |
| self.add_ty(m.ty); |
| } |
| |
| &ty::Ref(r, ty, _) => { |
| self.add_region(r); |
| self.add_ty(ty); |
| } |
| |
| &ty::Tuple(ref substs) => { |
| self.add_substs(substs); |
| } |
| |
| &ty::FnDef(_, substs) => { |
| self.add_substs(substs); |
| } |
| |
| &ty::FnPtr(f) => { |
| self.add_fn_sig(f); |
| } |
| } |
| } |
| |
| fn add_ty(&mut self, ty: Ty<'_>) { |
| self.add_flags(ty.flags); |
| self.add_exclusive_binder(ty.outer_exclusive_binder); |
| } |
| |
| fn add_tys(&mut self, tys: &[Ty<'_>]) { |
| for &ty in tys { |
| self.add_ty(ty); |
| } |
| } |
| |
| fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) { |
| let mut computation = FlagComputation::new(); |
| |
| computation.add_tys(fn_sig.skip_binder().inputs()); |
| computation.add_ty(fn_sig.skip_binder().output()); |
| |
| self.add_bound_computation(&computation); |
| } |
| |
| fn add_region(&mut self, r: ty::Region<'_>) { |
| self.add_flags(r.type_flags()); |
| if let ty::ReLateBound(debruijn, _) = *r { |
| self.add_binder(debruijn); |
| } |
| } |
| |
| fn add_const(&mut self, c: &ty::Const<'_>) { |
| self.add_ty(c.ty); |
| match c.val { |
| ty::ConstKind::Unevaluated(_, substs, _) => { |
| self.add_substs(substs); |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| } |
| ty::ConstKind::Infer(infer) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_CT_INFER); |
| match infer { |
| InferConst::Fresh(_) => {} |
| InferConst::Var(_) => self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX), |
| } |
| } |
| ty::ConstKind::Bound(debruijn, _) => self.add_binder(debruijn), |
| ty::ConstKind::Param(_) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_flags(TypeFlags::HAS_PARAMS); |
| } |
| ty::ConstKind::Placeholder(_) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER); |
| } |
| ty::ConstKind::Value(_) => {} |
| } |
| } |
| |
| fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) { |
| self.add_substs(projection.substs); |
| self.add_ty(projection.ty); |
| } |
| |
| fn add_projection_ty(&mut self, projection_ty: &ty::ProjectionTy<'_>) { |
| self.add_substs(projection_ty.substs); |
| } |
| |
| fn add_substs(&mut self, substs: SubstsRef<'_>) { |
| for kind in substs { |
| match kind.unpack() { |
| GenericArgKind::Type(ty) => self.add_ty(ty), |
| GenericArgKind::Lifetime(lt) => self.add_region(lt), |
| GenericArgKind::Const(ct) => self.add_const(ct), |
| } |
| } |
| } |
| } |
