1 use crate::ty::subst::{SubstsRef, UnpackedKind};
2 use crate::ty::{self, Ty, TypeFlags, TypeFoldable, InferConst};
3 use crate::mir::interpret::ConstValue;
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 {
16 flags: TypeFlags::empty(),
17 outer_exclusive_binder: ty::INNERMOST,
21 pub fn for_sty(st: &ty::TyKind<'_>) -> FlagComputation {
22 let mut result = FlagComputation::new();
27 pub fn for_const(c: &ty::Const<'_>) -> TypeFlags {
28 let mut result = FlagComputation::new();
33 fn add_flags(&mut self, flags: TypeFlags) {
34 self.flags = self.flags | (flags & TypeFlags::NOMINAL_FLAGS);
37 /// indicates that `self` refers to something at binding level `binder`
38 fn add_binder(&mut self, binder: ty::DebruijnIndex) {
39 let exclusive_binder = binder.shifted_in(1);
40 self.add_exclusive_binder(exclusive_binder);
43 /// indicates that `self` refers to something *inside* binding
44 /// level `binder` -- not bound by `binder`, but bound by the next
45 /// binder internal to it
46 fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
47 self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
50 /// Adds the flags/depth from a set of types that appear within the current type, but within a
52 fn add_bound_computation(&mut self, computation: &FlagComputation) {
53 self.add_flags(computation.flags);
55 // The types that contributed to `computation` occurred within
56 // a region binder, so subtract one from the region depth
57 // within when adding the depth to `self`.
58 let outer_exclusive_binder = computation.outer_exclusive_binder;
59 if outer_exclusive_binder > ty::INNERMOST {
60 self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
61 } // otherwise, this binder captures nothing
64 fn add_sty(&mut self, st: &ty::TyKind<'_>) {
76 // You might think that we could just return Error for
77 // any type containing Error as a component, and get
78 // rid of the TypeFlags::HAS_TY_ERR flag -- likewise for ty_bot (with
79 // the exception of function types that return bot).
80 // But doing so caused sporadic memory corruption, and
81 // neither I (tjc) nor nmatsakis could figure out why,
82 // so we're doing it this way.
84 self.add_flags(TypeFlags::HAS_TY_ERR)
87 &ty::Param(ref p) => {
88 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
90 self.add_flags(TypeFlags::HAS_SELF);
92 self.add_flags(TypeFlags::HAS_PARAMS);
96 &ty::Generator(_, ref substs, _) => {
97 self.add_flags(TypeFlags::HAS_TY_CLOSURE);
98 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
99 self.add_substs(&substs.substs);
102 &ty::GeneratorWitness(ref ts) => {
103 let mut computation = FlagComputation::new();
104 computation.add_tys(&ts.skip_binder()[..]);
105 self.add_bound_computation(&computation);
108 &ty::Closure(_, ref substs) => {
109 self.add_flags(TypeFlags::HAS_TY_CLOSURE);
110 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
111 self.add_substs(&substs.substs);
114 &ty::Bound(debruijn, _) => {
115 self.add_binder(debruijn);
118 &ty::Placeholder(..) => {
119 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
122 &ty::Infer(infer) => {
123 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); // it might, right?
124 self.add_flags(TypeFlags::HAS_TY_INFER);
128 ty::FreshFloatTy(_) => {
134 self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX)
139 &ty::Adt(_, substs) => {
140 self.add_substs(substs);
143 &ty::Projection(ref data) => {
144 // currently we can't normalize projections that
145 // include bound regions, so track those separately.
146 if !data.has_escaping_bound_vars() {
147 self.add_flags(TypeFlags::HAS_NORMALIZABLE_PROJECTION);
149 self.add_flags(TypeFlags::HAS_PROJECTION);
150 self.add_projection_ty(data);
153 &ty::UnnormalizedProjection(ref data) => {
154 self.add_flags(TypeFlags::HAS_PROJECTION);
155 self.add_projection_ty(data);
158 &ty::Opaque(_, substs) => {
159 self.add_flags(TypeFlags::HAS_PROJECTION);
160 self.add_substs(substs);
163 &ty::Dynamic(ref obj, r) => {
164 let mut computation = FlagComputation::new();
165 for predicate in obj.skip_binder().iter() {
167 ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs),
168 ty::ExistentialPredicate::Projection(p) => {
169 let mut proj_computation = FlagComputation::new();
170 proj_computation.add_existential_projection(&p);
171 self.add_bound_computation(&proj_computation);
173 ty::ExistentialPredicate::AutoTrait(_) => {}
176 self.add_bound_computation(&computation);
180 &ty::Array(tt, len) => {
189 &ty::RawPtr(ref m) => {
193 &ty::Ref(r, ty, _) => {
198 &ty::Tuple(ref substs) => {
199 self.add_substs(substs);
202 &ty::FnDef(_, substs) => {
203 self.add_substs(substs);
212 fn add_ty(&mut self, ty: Ty<'_>) {
213 self.add_flags(ty.flags);
214 self.add_exclusive_binder(ty.outer_exclusive_binder);
217 fn add_tys(&mut self, tys: &[Ty<'_>]) {
223 fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) {
224 let mut computation = FlagComputation::new();
226 computation.add_tys(fn_sig.skip_binder().inputs());
227 computation.add_ty(fn_sig.skip_binder().output());
229 self.add_bound_computation(&computation);
232 fn add_region(&mut self, r: ty::Region<'_>) {
233 self.add_flags(r.type_flags());
234 if let ty::ReLateBound(debruijn, _) = *r {
235 self.add_binder(debruijn);
239 fn add_const(&mut self, c: &ty::Const<'_>) {
242 ConstValue::Unevaluated(_, substs) => {
243 self.add_substs(substs);
244 self.add_flags(TypeFlags::HAS_NORMALIZABLE_PROJECTION | TypeFlags::HAS_PROJECTION);
246 ConstValue::Infer(infer) => {
247 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_CT_INFER);
249 InferConst::Fresh(_) => {}
250 InferConst::Canonical(debruijn, _) => self.add_binder(debruijn),
251 InferConst::Var(_) => self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX),
254 ConstValue::Param(_) => {
255 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_PARAMS);
257 ConstValue::Placeholder(_) => {
258 self.add_flags(TypeFlags::HAS_FREE_REGIONS | TypeFlags::HAS_CT_PLACEHOLDER);
264 fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
265 self.add_substs(projection.substs);
266 self.add_ty(projection.ty);
269 fn add_projection_ty(&mut self, projection_ty: &ty::ProjectionTy<'_>) {
270 self.add_substs(projection_ty.substs);
273 fn add_substs(&mut self, substs: SubstsRef<'_>) {
275 match kind.unpack() {
276 UnpackedKind::Type(ty) => self.add_ty(ty),
277 UnpackedKind::Lifetime(lt) => self.add_region(lt),
278 UnpackedKind::Const(ct) => self.add_const(ct),