1 use crate::ty::subst::{GenericArg, GenericArgKind};
2 use crate::ty::{self, InferConst, Ty, TypeFlags};
6 pub struct FlagComputation {
9 // see `TyS::outer_exclusive_binder` for details
10 pub outer_exclusive_binder: ty::DebruijnIndex,
13 impl FlagComputation {
14 fn new() -> FlagComputation {
15 FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST }
18 #[allow(rustc::usage_of_ty_tykind)]
19 pub fn for_kind(kind: &ty::TyKind<'_>) -> FlagComputation {
20 let mut result = FlagComputation::new();
21 result.add_kind(kind);
25 pub fn for_predicate(kind: &ty::PredicateKind<'_>) -> FlagComputation {
26 let mut result = FlagComputation::new();
27 result.add_predicate_kind(kind);
31 pub fn for_const(c: &ty::Const<'_>) -> TypeFlags {
32 let mut result = FlagComputation::new();
37 fn add_flags(&mut self, flags: TypeFlags) {
38 self.flags = self.flags | flags;
41 /// indicates that `self` refers to something at binding level `binder`
42 fn add_bound_var(&mut self, binder: ty::DebruijnIndex) {
43 let exclusive_binder = binder.shifted_in(1);
44 self.add_exclusive_binder(exclusive_binder);
47 /// indicates that `self` refers to something *inside* binding
48 /// level `binder` -- not bound by `binder`, but bound by the next
49 /// binder internal to it
50 fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
51 self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
54 /// Adds the flags/depth from a set of types that appear within the current type, but within a
56 fn add_bound_computation(&mut self, computation: FlagComputation) {
57 self.add_flags(computation.flags);
59 // The types that contributed to `computation` occurred within
60 // a region binder, so subtract one from the region depth
61 // within when adding the depth to `self`.
62 let outer_exclusive_binder = computation.outer_exclusive_binder;
63 if outer_exclusive_binder > ty::INNERMOST {
64 self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
65 } // otherwise, this binder captures nothing
68 #[allow(rustc::usage_of_ty_tykind)]
69 fn add_kind(&mut self, kind: &ty::TyKind<'_>) {
78 | &ty::Foreign(..) => {}
80 &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
83 self.add_flags(TypeFlags::HAS_TY_PARAM);
84 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
87 &ty::Generator(_, ref substs, _) => {
88 self.add_flags(TypeFlags::MAY_POLYMORPHIZE);
90 let substs = substs.as_generator();
91 let should_remove_further_specializable =
92 !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
93 self.add_substs(substs.parent_substs());
94 if should_remove_further_specializable {
95 self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
98 self.add_ty(substs.resume_ty());
99 self.add_ty(substs.return_ty());
100 self.add_ty(substs.witness());
101 self.add_ty(substs.yield_ty());
102 self.add_ty(substs.tupled_upvars_ty());
105 &ty::GeneratorWitness(ts) => {
106 let mut computation = FlagComputation::new();
107 computation.add_tys(ts.skip_binder());
108 self.add_bound_computation(computation);
111 &ty::Closure(_, substs) => {
112 self.add_flags(TypeFlags::MAY_POLYMORPHIZE);
114 let substs = substs.as_closure();
115 let should_remove_further_specializable =
116 !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
117 self.add_substs(substs.parent_substs());
118 if should_remove_further_specializable {
119 self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
122 self.add_ty(substs.sig_as_fn_ptr_ty());
123 self.add_ty(substs.kind_ty());
124 self.add_ty(substs.tupled_upvars_ty());
127 &ty::Bound(debruijn, _) => {
128 self.add_bound_var(debruijn);
131 &ty::Placeholder(..) => {
132 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
133 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
136 &ty::Infer(infer) => {
137 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
139 ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {}
141 ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
142 self.add_flags(TypeFlags::HAS_TY_INFER)
147 &ty::Adt(_, substs) => {
148 self.add_substs(substs);
151 &ty::Projection(data) => {
152 self.add_flags(TypeFlags::HAS_TY_PROJECTION);
153 self.add_projection_ty(data);
156 &ty::Opaque(_, substs) => {
157 self.add_flags(TypeFlags::HAS_TY_OPAQUE);
158 self.add_substs(substs);
161 &ty::Dynamic(ref obj, r) => {
162 let mut computation = FlagComputation::new();
163 for predicate in obj.skip_binder().iter() {
165 ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs),
166 ty::ExistentialPredicate::Projection(p) => {
167 let mut proj_computation = FlagComputation::new();
168 proj_computation.add_existential_projection(&p);
169 self.add_bound_computation(proj_computation);
171 ty::ExistentialPredicate::AutoTrait(_) => {}
174 self.add_bound_computation(computation);
178 &ty::Array(tt, len) => {
183 &ty::Slice(tt) => self.add_ty(tt),
185 &ty::RawPtr(ref m) => {
189 &ty::Ref(r, ty, _) => {
194 &ty::Tuple(ref substs) => {
195 self.add_substs(substs);
198 &ty::FnDef(_, substs) => {
199 self.add_flags(TypeFlags::MAY_POLYMORPHIZE);
201 self.add_substs(substs);
210 fn add_predicate_kind(&mut self, kind: &ty::PredicateKind<'_>) {
212 ty::PredicateKind::ForAll(binder) => {
213 let mut computation = FlagComputation::new();
215 computation.add_predicate_atom(binder.skip_binder());
217 self.add_bound_computation(computation);
219 &ty::PredicateKind::Atom(atom) => self.add_predicate_atom(atom),
223 fn add_predicate_atom(&mut self, atom: ty::PredicateAtom<'_>) {
225 ty::PredicateAtom::Trait(trait_pred, _constness) => {
226 self.add_substs(trait_pred.trait_ref.substs);
228 ty::PredicateAtom::RegionOutlives(ty::OutlivesPredicate(a, b)) => {
232 ty::PredicateAtom::TypeOutlives(ty::OutlivesPredicate(ty, region)) => {
234 self.add_region(region);
236 ty::PredicateAtom::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
240 ty::PredicateAtom::Projection(ty::ProjectionPredicate { projection_ty, ty }) => {
241 self.add_projection_ty(projection_ty);
244 ty::PredicateAtom::WellFormed(arg) => {
245 self.add_substs(slice::from_ref(&arg));
247 ty::PredicateAtom::ObjectSafe(_def_id) => {}
248 ty::PredicateAtom::ClosureKind(_def_id, substs, _kind) => {
249 self.add_substs(substs);
251 ty::PredicateAtom::ConstEvaluatable(_def_id, substs) => {
252 self.add_substs(substs);
254 ty::PredicateAtom::ConstEquate(expected, found) => {
255 self.add_const(expected);
256 self.add_const(found);
261 fn add_ty(&mut self, ty: Ty<'_>) {
262 self.add_flags(ty.flags);
263 self.add_exclusive_binder(ty.outer_exclusive_binder);
266 fn add_tys(&mut self, tys: &[Ty<'_>]) {
272 fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) {
273 let mut computation = FlagComputation::new();
275 computation.add_tys(fn_sig.skip_binder().inputs());
276 computation.add_ty(fn_sig.skip_binder().output());
278 self.add_bound_computation(computation);
281 fn add_region(&mut self, r: ty::Region<'_>) {
282 self.add_flags(r.type_flags());
283 if let ty::ReLateBound(debruijn, _) = *r {
284 self.add_bound_var(debruijn);
288 fn add_const(&mut self, c: &ty::Const<'_>) {
291 ty::ConstKind::Unevaluated(_, substs, _) => {
292 self.add_substs(substs);
293 self.add_flags(TypeFlags::HAS_CT_PROJECTION);
295 ty::ConstKind::Infer(infer) => {
296 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
298 InferConst::Fresh(_) => {}
299 InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER),
302 ty::ConstKind::Bound(debruijn, _) => {
303 self.add_bound_var(debruijn);
305 ty::ConstKind::Param(_) => {
306 self.add_flags(TypeFlags::HAS_CT_PARAM);
307 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
309 ty::ConstKind::Placeholder(_) => {
310 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
311 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
313 ty::ConstKind::Value(_) => {}
314 ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
318 fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
319 self.add_substs(projection.substs);
320 self.add_ty(projection.ty);
323 fn add_projection_ty(&mut self, projection_ty: ty::ProjectionTy<'_>) {
324 self.add_substs(projection_ty.substs);
327 fn add_substs(&mut self, substs: &[GenericArg<'_>]) {
329 match kind.unpack() {
330 GenericArgKind::Type(ty) => self.add_ty(ty),
331 GenericArgKind::Lifetime(lt) => self.add_region(lt),
332 GenericArgKind::Const(ct) => self.add_const(ct),