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 #[allow(rustc::usage_of_ty_tykind)]
22 pub fn for_sty(st: &ty::TyKind<'_>) -> FlagComputation {
23 let mut result = FlagComputation::new();
28 pub fn for_const(c: &ty::Const<'_>) -> TypeFlags {
29 let mut result = FlagComputation::new();
34 fn add_flags(&mut self, flags: TypeFlags) {
35 self.flags = self.flags | (flags & TypeFlags::NOMINAL_FLAGS);
38 /// indicates that `self` refers to something at binding level `binder`
39 fn add_binder(&mut self, binder: ty::DebruijnIndex) {
40 let exclusive_binder = binder.shifted_in(1);
41 self.add_exclusive_binder(exclusive_binder);
44 /// indicates that `self` refers to something *inside* binding
45 /// level `binder` -- not bound by `binder`, but bound by the next
46 /// binder internal to it
47 fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
48 self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
51 /// Adds the flags/depth from a set of types that appear within the current type, but within a
53 fn add_bound_computation(&mut self, computation: &FlagComputation) {
54 self.add_flags(computation.flags);
56 // The types that contributed to `computation` occurred within
57 // a region binder, so subtract one from the region depth
58 // within when adding the depth to `self`.
59 let outer_exclusive_binder = computation.outer_exclusive_binder;
60 if outer_exclusive_binder > ty::INNERMOST {
61 self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
62 } // otherwise, this binder captures nothing
65 #[allow(rustc::usage_of_ty_tykind)]
66 fn add_sty(&mut self, st: &ty::TyKind<'_>) {
78 // You might think that we could just return Error for
79 // any type containing Error as a component, and get
80 // rid of the TypeFlags::HAS_TY_ERR flag -- likewise for ty_bot (with
81 // the exception of function types that return bot).
82 // But doing so caused sporadic memory corruption, and
83 // neither I (tjc) nor nmatsakis could figure out why,
84 // so we're doing it this way.
86 self.add_flags(TypeFlags::HAS_TY_ERR)
89 &ty::Param(ref p) => {
90 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
92 self.add_flags(TypeFlags::HAS_SELF);
94 self.add_flags(TypeFlags::HAS_PARAMS);
98 &ty::Generator(_, ref substs, _) => {
99 self.add_flags(TypeFlags::HAS_TY_CLOSURE);
100 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
101 self.add_substs(&substs.substs);
104 &ty::GeneratorWitness(ref ts) => {
105 let mut computation = FlagComputation::new();
106 computation.add_tys(&ts.skip_binder()[..]);
107 self.add_bound_computation(&computation);
110 &ty::Closure(_, ref substs) => {
111 self.add_flags(TypeFlags::HAS_TY_CLOSURE);
112 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
113 self.add_substs(&substs.substs);
116 &ty::Bound(debruijn, _) => {
117 self.add_binder(debruijn);
120 &ty::Placeholder(..) => {
121 self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
124 &ty::Infer(infer) => {
125 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); // it might, right?
126 self.add_flags(TypeFlags::HAS_TY_INFER);
130 ty::FreshFloatTy(_) => {
136 self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX)
141 &ty::Adt(_, substs) => {
142 self.add_substs(substs);
145 &ty::Projection(ref data) => {
146 // currently we can't normalize projections that
147 // include bound regions, so track those separately.
148 if !data.has_escaping_bound_vars() {
149 self.add_flags(TypeFlags::HAS_NORMALIZABLE_PROJECTION);
151 self.add_flags(TypeFlags::HAS_PROJECTION);
152 self.add_projection_ty(data);
155 &ty::UnnormalizedProjection(ref data) => {
156 self.add_flags(TypeFlags::HAS_PROJECTION);
157 self.add_projection_ty(data);
160 &ty::Opaque(_, substs) => {
161 self.add_flags(TypeFlags::HAS_PROJECTION);
162 self.add_substs(substs);
165 &ty::Dynamic(ref obj, r) => {
166 let mut computation = FlagComputation::new();
167 for predicate in obj.skip_binder().iter() {
169 ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs),
170 ty::ExistentialPredicate::Projection(p) => {
171 let mut proj_computation = FlagComputation::new();
172 proj_computation.add_existential_projection(&p);
173 self.add_bound_computation(&proj_computation);
175 ty::ExistentialPredicate::AutoTrait(_) => {}
178 self.add_bound_computation(&computation);
182 &ty::Array(tt, len) => {
191 &ty::RawPtr(ref m) => {
195 &ty::Ref(r, ty, _) => {
200 &ty::Tuple(ref substs) => {
201 self.add_substs(substs);
204 &ty::FnDef(_, substs) => {
205 self.add_substs(substs);
214 fn add_ty(&mut self, ty: Ty<'_>) {
215 self.add_flags(ty.flags);
216 self.add_exclusive_binder(ty.outer_exclusive_binder);
219 fn add_tys(&mut self, tys: &[Ty<'_>]) {
225 fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig<'_>) {
226 let mut computation = FlagComputation::new();
228 computation.add_tys(fn_sig.skip_binder().inputs());
229 computation.add_ty(fn_sig.skip_binder().output());
231 self.add_bound_computation(&computation);
234 fn add_region(&mut self, r: ty::Region<'_>) {
235 self.add_flags(r.type_flags());
236 if let ty::ReLateBound(debruijn, _) = *r {
237 self.add_binder(debruijn);
241 fn add_const(&mut self, c: &ty::Const<'_>) {
244 ConstValue::Unevaluated(_, substs) => {
245 self.add_substs(substs);
246 self.add_flags(TypeFlags::HAS_NORMALIZABLE_PROJECTION | TypeFlags::HAS_PROJECTION);
248 ConstValue::Infer(infer) => {
249 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_CT_INFER);
251 InferConst::Fresh(_) => {}
252 InferConst::Canonical(debruijn, _) => self.add_binder(debruijn),
253 InferConst::Var(_) => self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX),
256 ConstValue::Param(_) => {
257 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_PARAMS);
259 ConstValue::Placeholder(_) => {
260 self.add_flags(TypeFlags::HAS_FREE_REGIONS | TypeFlags::HAS_CT_PLACEHOLDER);
266 fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
267 self.add_substs(projection.substs);
268 self.add_ty(projection.ty);
271 fn add_projection_ty(&mut self, projection_ty: &ty::ProjectionTy<'_>) {
272 self.add_substs(projection_ty.substs);
275 fn add_substs(&mut self, substs: SubstsRef<'_>) {
277 match kind.unpack() {
278 UnpackedKind::Type(ty) => self.add_ty(ty),
279 UnpackedKind::Lifetime(lt) => self.add_region(lt),
280 UnpackedKind::Const(ct) => self.add_const(ct),