1 use crate::ty::subst::{GenericArgKind, SubstsRef};
2 use crate::ty::{self, InferConst, Ty, TypeFlags};
5 pub struct FlagComputation {
8 // see `TyS::outer_exclusive_binder` for details
9 pub outer_exclusive_binder: ty::DebruijnIndex,
12 impl FlagComputation {
13 fn new() -> FlagComputation {
14 FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST }
17 #[allow(rustc::usage_of_ty_tykind)]
18 pub fn for_kind(kind: &ty::TyKind<'_>) -> FlagComputation {
19 let mut result = FlagComputation::new();
20 result.add_kind(kind);
24 pub fn for_const(c: &ty::Const<'_>) -> TypeFlags {
25 let mut result = FlagComputation::new();
30 fn add_flags(&mut self, flags: TypeFlags) {
31 self.flags = self.flags | (flags & TypeFlags::NOMINAL_FLAGS);
34 /// indicates that `self` refers to something at binding level `binder`
35 fn add_binder(&mut self, binder: ty::DebruijnIndex) {
36 let exclusive_binder = binder.shifted_in(1);
37 self.add_exclusive_binder(exclusive_binder);
40 /// indicates that `self` refers to something *inside* binding
41 /// level `binder` -- not bound by `binder`, but bound by the next
42 /// binder internal to it
43 fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
44 self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
47 /// Adds the flags/depth from a set of types that appear within the current type, but within a
49 fn add_bound_computation(&mut self, computation: &FlagComputation) {
50 self.add_flags(computation.flags);
52 // The types that contributed to `computation` occurred within
53 // a region binder, so subtract one from the region depth
54 // within when adding the depth to `self`.
55 let outer_exclusive_binder = computation.outer_exclusive_binder;
56 if outer_exclusive_binder > ty::INNERMOST {
57 self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
58 } // otherwise, this binder captures nothing
61 #[allow(rustc::usage_of_ty_tykind)]
62 fn add_kind(&mut self, kind: &ty::TyKind<'_>) {
71 | &ty::Foreign(..) => {}
73 // You might think that we could just return Error for
74 // any type containing Error as a component, and get
75 // rid of the TypeFlags::HAS_TY_ERR flag -- likewise for ty_bot (with
76 // the exception of function types that return bot).
77 // But doing so caused sporadic memory corruption, and
78 // neither I (tjc) nor nmatsakis could figure out why,
79 // so we're doing it this way.
80 &ty::Error => self.add_flags(TypeFlags::HAS_TY_ERR),
83 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
84 self.add_flags(TypeFlags::HAS_PARAMS);
87 &ty::Generator(_, ref substs, _) => {
88 self.add_flags(TypeFlags::HAS_TY_CLOSURE);
89 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
90 self.add_substs(substs);
93 &ty::GeneratorWitness(ref ts) => {
94 let mut computation = FlagComputation::new();
95 computation.add_tys(&ts.skip_binder()[..]);
96 self.add_bound_computation(&computation);
99 &ty::Closure(_, ref substs) => {
100 self.add_flags(TypeFlags::HAS_TY_CLOSURE);
101 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
102 self.add_substs(substs);
105 &ty::Bound(debruijn, _) => {
106 self.add_binder(debruijn);
109 &ty::Placeholder(..) => {
110 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
111 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
114 &ty::Infer(infer) => {
115 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); // it might, right?
116 self.add_flags(TypeFlags::HAS_TY_INFER);
118 ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {}
120 ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
121 self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX)
126 &ty::Adt(_, substs) => {
127 self.add_substs(substs);
130 &ty::Projection(ref data) => {
131 self.add_flags(TypeFlags::HAS_PROJECTION);
132 self.add_projection_ty(data);
135 &ty::UnnormalizedProjection(ref data) => {
136 self.add_flags(TypeFlags::HAS_PROJECTION);
137 self.add_projection_ty(data);
140 &ty::Opaque(_, substs) => {
141 self.add_flags(TypeFlags::HAS_PROJECTION);
142 self.add_substs(substs);
145 &ty::Dynamic(ref obj, r) => {
146 let mut computation = FlagComputation::new();
147 for predicate in obj.skip_binder().iter() {
149 ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs),
150 ty::ExistentialPredicate::Projection(p) => {
151 let mut proj_computation = FlagComputation::new();
152 proj_computation.add_existential_projection(&p);
153 self.add_bound_computation(&proj_computation);
155 ty::ExistentialPredicate::AutoTrait(_) => {}
158 self.add_bound_computation(&computation);
162 &ty::Array(tt, len) => {
167 &ty::Slice(tt) => self.add_ty(tt),
169 &ty::RawPtr(ref m) => {
173 &ty::Ref(r, ty, _) => {
178 &ty::Tuple(ref substs) => {
179 self.add_substs(substs);
182 &ty::FnDef(_, substs) => {
183 self.add_substs(substs);
192 fn add_ty(&mut self, ty: Ty<'_>) {
193 self.add_flags(ty.flags);
194 self.add_exclusive_binder(ty.outer_exclusive_binder);
197 fn add_tys(&mut self, tys: &[Ty<'_>]) {
203 fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) {
204 let mut computation = FlagComputation::new();
206 computation.add_tys(fn_sig.skip_binder().inputs());
207 computation.add_ty(fn_sig.skip_binder().output());
209 self.add_bound_computation(&computation);
212 fn add_region(&mut self, r: ty::Region<'_>) {
213 self.add_flags(r.type_flags());
214 if let ty::ReLateBound(debruijn, _) = *r {
215 self.add_binder(debruijn);
219 fn add_const(&mut self, c: &ty::Const<'_>) {
222 ty::ConstKind::Unevaluated(_, substs, _) => {
223 self.add_substs(substs);
224 self.add_flags(TypeFlags::HAS_PROJECTION);
226 ty::ConstKind::Infer(infer) => {
227 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_CT_INFER);
229 InferConst::Fresh(_) => {}
230 InferConst::Var(_) => self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX),
233 ty::ConstKind::Bound(debruijn, _) => self.add_binder(debruijn),
234 ty::ConstKind::Param(_) => {
235 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
236 self.add_flags(TypeFlags::HAS_PARAMS);
238 ty::ConstKind::Placeholder(_) => {
239 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
240 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
242 ty::ConstKind::Value(_) => {}
246 fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
247 self.add_substs(projection.substs);
248 self.add_ty(projection.ty);
251 fn add_projection_ty(&mut self, projection_ty: &ty::ProjectionTy<'_>) {
252 self.add_substs(projection_ty.substs);
255 fn add_substs(&mut self, substs: SubstsRef<'_>) {
257 match kind.unpack() {
258 GenericArgKind::Type(ty) => self.add_ty(ty),
259 GenericArgKind::Lifetime(lt) => self.add_region(lt),
260 GenericArgKind::Const(ct) => self.add_const(ct),