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<'tcx>(binder: ty::Binder<'tcx, ty::PredicateKind<'_>>) -> FlagComputation {
26 let mut result = FlagComputation::new();
27 result.add_predicate(binder);
31 pub fn for_const(c: &ty::Const<'_>) -> TypeFlags {
32 let mut result = FlagComputation::new();
37 pub fn for_unevaluated_const(uv: ty::Unevaluated<'_>) -> TypeFlags {
38 let mut result = FlagComputation::new();
39 result.add_unevaluated_const(uv);
43 fn add_flags(&mut self, flags: TypeFlags) {
44 self.flags = self.flags | flags;
47 /// indicates that `self` refers to something at binding level `binder`
48 fn add_bound_var(&mut self, binder: ty::DebruijnIndex) {
49 let exclusive_binder = binder.shifted_in(1);
50 self.add_exclusive_binder(exclusive_binder);
53 /// indicates that `self` refers to something *inside* binding
54 /// level `binder` -- not bound by `binder`, but bound by the next
55 /// binder internal to it
56 fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
57 self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
60 /// Adds the flags/depth from a set of types that appear within the current type, but within a
62 fn bound_computation<T, F>(&mut self, value: ty::Binder<'_, T>, f: F)
64 F: FnOnce(&mut Self, T),
66 let mut computation = FlagComputation::new();
68 if !value.bound_vars().is_empty() {
69 computation.flags = computation.flags | TypeFlags::HAS_RE_LATE_BOUND;
72 f(&mut computation, value.skip_binder());
74 self.add_flags(computation.flags);
76 // The types that contributed to `computation` occurred within
77 // a region binder, so subtract one from the region depth
78 // within when adding the depth to `self`.
79 let outer_exclusive_binder = computation.outer_exclusive_binder;
80 if outer_exclusive_binder > ty::INNERMOST {
81 self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
82 } // otherwise, this binder captures nothing
85 #[allow(rustc::usage_of_ty_tykind)]
86 fn add_kind(&mut self, kind: &ty::TyKind<'_>) {
95 | &ty::Foreign(..) => {}
97 &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
100 self.add_flags(TypeFlags::HAS_KNOWN_TY_PARAM);
101 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
104 &ty::Generator(_, ref substs, _) => {
105 let substs = substs.as_generator();
106 let should_remove_further_specializable =
107 !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
108 self.add_substs(substs.parent_substs());
109 if should_remove_further_specializable {
110 self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
113 self.add_ty(substs.resume_ty());
114 self.add_ty(substs.return_ty());
115 self.add_ty(substs.witness());
116 self.add_ty(substs.yield_ty());
117 self.add_ty(substs.tupled_upvars_ty());
120 &ty::GeneratorWitness(ts) => {
121 self.bound_computation(ts, |flags, ts| flags.add_tys(ts));
124 &ty::Closure(_, substs) => {
125 let substs = substs.as_closure();
126 let should_remove_further_specializable =
127 !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
128 self.add_substs(substs.parent_substs());
129 if should_remove_further_specializable {
130 self.flags -= TypeFlags::STILL_FURTHER_SPECIALIZABLE;
133 self.add_ty(substs.sig_as_fn_ptr_ty());
134 self.add_ty(substs.kind_ty());
135 self.add_ty(substs.tupled_upvars_ty());
138 &ty::Bound(debruijn, _) => {
139 self.add_bound_var(debruijn);
142 &ty::Placeholder(..) => {
143 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
144 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
147 &ty::Infer(infer) => {
148 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
150 ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {
151 self.add_flags(TypeFlags::HAS_TY_FRESH)
154 ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
155 self.add_flags(TypeFlags::HAS_TY_INFER)
160 &ty::Adt(_, substs) => {
161 self.add_substs(substs);
164 &ty::Projection(data) => {
165 self.add_flags(TypeFlags::HAS_TY_PROJECTION);
166 self.add_projection_ty(data);
169 &ty::Opaque(_, substs) => {
170 self.add_flags(TypeFlags::HAS_TY_OPAQUE);
171 self.add_substs(substs);
174 &ty::Dynamic(obj, r) => {
175 for predicate in obj.iter() {
176 self.bound_computation(predicate, |computation, predicate| match predicate {
177 ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs),
178 ty::ExistentialPredicate::Projection(p) => {
179 computation.add_existential_projection(&p);
181 ty::ExistentialPredicate::AutoTrait(_) => {}
188 &ty::Array(tt, len) => {
193 &ty::Slice(tt) => self.add_ty(tt),
195 &ty::RawPtr(ref m) => {
199 &ty::Ref(r, ty, _) => {
204 &ty::Tuple(ref substs) => {
205 self.add_substs(substs);
208 &ty::FnDef(_, substs) => {
209 self.add_substs(substs);
212 &ty::FnPtr(fn_sig) => self.bound_computation(fn_sig, |computation, fn_sig| {
213 computation.add_tys(fn_sig.inputs());
214 computation.add_ty(fn_sig.output());
219 fn add_predicate(&mut self, binder: ty::Binder<'_, ty::PredicateKind<'_>>) {
220 self.bound_computation(binder, |computation, atom| computation.add_predicate_atom(atom));
223 fn add_predicate_atom(&mut self, atom: ty::PredicateKind<'_>) {
225 ty::PredicateKind::Trait(trait_pred) => {
226 self.add_substs(trait_pred.trait_ref.substs);
228 ty::PredicateKind::RegionOutlives(ty::OutlivesPredicate(a, b)) => {
232 ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(ty, region)) => {
234 self.add_region(region);
236 ty::PredicateKind::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
240 ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => {
244 ty::PredicateKind::Projection(ty::ProjectionPredicate { projection_ty, ty }) => {
245 self.add_projection_ty(projection_ty);
248 ty::PredicateKind::WellFormed(arg) => {
249 self.add_substs(slice::from_ref(&arg));
251 ty::PredicateKind::ObjectSafe(_def_id) => {}
252 ty::PredicateKind::ClosureKind(_def_id, substs, _kind) => {
253 self.add_substs(substs);
255 ty::PredicateKind::ConstEvaluatable(uv) => {
256 self.add_unevaluated_const(uv);
258 ty::PredicateKind::ConstEquate(expected, found) => {
259 self.add_const(expected);
260 self.add_const(found);
262 ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
268 fn add_ty(&mut self, ty: Ty<'_>) {
269 self.add_flags(ty.flags());
270 self.add_exclusive_binder(ty.outer_exclusive_binder);
273 fn add_tys(&mut self, tys: &[Ty<'_>]) {
279 fn add_region(&mut self, r: ty::Region<'_>) {
280 self.add_flags(r.type_flags());
281 if let ty::ReLateBound(debruijn, _) = *r {
282 self.add_bound_var(debruijn);
286 fn add_const(&mut self, c: &ty::Const<'_>) {
289 ty::ConstKind::Unevaluated(unevaluated) => self.add_unevaluated_const(unevaluated),
290 ty::ConstKind::Infer(infer) => {
291 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
293 InferConst::Fresh(_) => self.add_flags(TypeFlags::HAS_CT_FRESH),
294 InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER),
297 ty::ConstKind::Bound(debruijn, _) => {
298 self.add_bound_var(debruijn);
300 ty::ConstKind::Param(_) => {
301 self.add_flags(TypeFlags::HAS_KNOWN_CT_PARAM);
302 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
304 ty::ConstKind::Placeholder(_) => {
305 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
306 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
308 ty::ConstKind::Value(_) => {}
309 ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
313 fn add_unevaluated_const<P>(&mut self, ct: ty::Unevaluated<'_, P>) {
314 // The generic arguments of unevaluated consts are a bit special,
315 // see the `rustc-dev-guide` for more information.
317 // FIXME(@lcnr): Actually add a link here.
318 if let Some(substs) = ct.substs_ {
319 // If they are available, we treat them as ordinary generic arguments.
320 self.add_substs(substs);
322 // Otherwise, we add `HAS_UNKNOWN_DEFAULT_CONST_SUBSTS` to signify
323 // that our const may potentially refer to generic parameters.
325 // Note that depending on which generic parameters are actually
326 // used in this constant, we may not actually refer to any generic
327 // parameters at all.
328 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
329 self.add_flags(TypeFlags::HAS_UNKNOWN_DEFAULT_CONST_SUBSTS);
331 self.add_flags(TypeFlags::HAS_CT_PROJECTION);
334 fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
335 self.add_substs(projection.substs);
336 self.add_ty(projection.ty);
339 fn add_projection_ty(&mut self, projection_ty: ty::ProjectionTy<'_>) {
340 self.add_substs(projection_ty.substs);
343 fn add_substs(&mut self, substs: &[GenericArg<'_>]) {
345 match kind.unpack() {
346 GenericArgKind::Type(ty) => self.add_ty(ty),
347 GenericArgKind::Lifetime(lt) => self.add_region(lt),
348 GenericArgKind::Const(ct) => self.add_const(ct),