rustc_middle/ty/
flags.rs

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1use std::slice;
2
3use crate::ty::{self, GenericArg, GenericArgKind, InferConst, Ty, TypeFlags};
4
5#[derive(Debug)]
6pub struct FlagComputation {
7    pub flags: TypeFlags,
8
9    /// see `Ty::outer_exclusive_binder` for details
10    pub outer_exclusive_binder: ty::DebruijnIndex,
11}
12
13impl FlagComputation {
14    fn new() -> FlagComputation {
15        FlagComputation { flags: TypeFlags::empty(), outer_exclusive_binder: ty::INNERMOST }
16    }
17
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);
22        result
23    }
24
25    pub fn for_predicate(binder: ty::Binder<'_, ty::PredicateKind<'_>>) -> FlagComputation {
26        let mut result = FlagComputation::new();
27        result.add_predicate(binder);
28        result
29    }
30
31    pub fn for_const_kind(kind: &ty::ConstKind<'_>) -> FlagComputation {
32        let mut result = FlagComputation::new();
33        result.add_const_kind(kind);
34        result
35    }
36
37    pub fn for_clauses(clauses: &[ty::Clause<'_>]) -> FlagComputation {
38        let mut result = FlagComputation::new();
39        for c in clauses {
40            result.add_flags(c.as_predicate().flags());
41            result.add_exclusive_binder(c.as_predicate().outer_exclusive_binder());
42        }
43        result
44    }
45
46    fn add_flags(&mut self, flags: TypeFlags) {
47        self.flags = self.flags | flags;
48    }
49
50    /// indicates that `self` refers to something at binding level `binder`
51    fn add_bound_var(&mut self, binder: ty::DebruijnIndex) {
52        let exclusive_binder = binder.shifted_in(1);
53        self.add_exclusive_binder(exclusive_binder);
54    }
55
56    /// indicates that `self` refers to something *inside* binding
57    /// level `binder` -- not bound by `binder`, but bound by the next
58    /// binder internal to it
59    fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) {
60        self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder);
61    }
62
63    /// Adds the flags/depth from a set of types that appear within the current type, but within a
64    /// region binder.
65    fn bound_computation<T, F>(&mut self, value: ty::Binder<'_, T>, f: F)
66    where
67        F: FnOnce(&mut Self, T),
68    {
69        let mut computation = FlagComputation::new();
70
71        if !value.bound_vars().is_empty() {
72            computation.add_flags(TypeFlags::HAS_BINDER_VARS);
73        }
74
75        f(&mut computation, value.skip_binder());
76
77        self.add_flags(computation.flags);
78
79        // The types that contributed to `computation` occurred within
80        // a region binder, so subtract one from the region depth
81        // within when adding the depth to `self`.
82        let outer_exclusive_binder = computation.outer_exclusive_binder;
83        if outer_exclusive_binder > ty::INNERMOST {
84            self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1));
85        } // otherwise, this binder captures nothing
86    }
87
88    #[allow(rustc::usage_of_ty_tykind)]
89    fn add_kind(&mut self, kind: &ty::TyKind<'_>) {
90        match kind {
91            &ty::Bool
92            | &ty::Char
93            | &ty::Int(_)
94            | &ty::Float(_)
95            | &ty::Uint(_)
96            | &ty::Never
97            | &ty::Str
98            | &ty::Foreign(..) => {}
99
100            &ty::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
101
102            &ty::Param(_) => {
103                self.add_flags(TypeFlags::HAS_TY_PARAM);
104            }
105
106            &ty::Closure(_, args)
107            | &ty::Coroutine(_, args)
108            | &ty::CoroutineClosure(_, args)
109            | &ty::CoroutineWitness(_, args) => {
110                self.add_args(args);
111            }
112
113            &ty::Bound(debruijn, _) => {
114                self.add_bound_var(debruijn);
115                self.add_flags(TypeFlags::HAS_TY_BOUND);
116            }
117
118            &ty::Placeholder(..) => {
119                self.add_flags(TypeFlags::HAS_TY_PLACEHOLDER);
120            }
121
122            &ty::Infer(infer) => match infer {
123                ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_) => {
124                    self.add_flags(TypeFlags::HAS_TY_FRESH)
125                }
126
127                ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => {
128                    self.add_flags(TypeFlags::HAS_TY_INFER)
129                }
130            },
131
132            &ty::Adt(_, args) => {
133                self.add_args(args);
134            }
135
136            &ty::Alias(kind, data) => {
137                self.add_flags(match kind {
138                    ty::Projection => TypeFlags::HAS_TY_PROJECTION,
139                    ty::Weak => TypeFlags::HAS_TY_WEAK,
140                    ty::Opaque => TypeFlags::HAS_TY_OPAQUE,
141                    ty::Inherent => TypeFlags::HAS_TY_INHERENT,
142                });
143
144                self.add_alias_ty(data);
145            }
146
147            &ty::Dynamic(obj, r, _) => {
148                for predicate in obj.iter() {
149                    self.bound_computation(predicate, |computation, predicate| match predicate {
150                        ty::ExistentialPredicate::Trait(tr) => computation.add_args(tr.args),
151                        ty::ExistentialPredicate::Projection(p) => {
152                            computation.add_existential_projection(&p);
153                        }
154                        ty::ExistentialPredicate::AutoTrait(_) => {}
155                    });
156                }
157
158                self.add_region(r);
159            }
160
161            &ty::Array(tt, len) => {
162                self.add_ty(tt);
163                self.add_const(len);
164            }
165
166            &ty::Pat(ty, pat) => {
167                self.add_ty(ty);
168                match *pat {
169                    ty::PatternKind::Range { start, end } => {
170                        self.add_const(start);
171                        self.add_const(end);
172                    }
173                }
174            }
175
176            &ty::Slice(tt) => self.add_ty(tt),
177
178            &ty::RawPtr(ty, _) => {
179                self.add_ty(ty);
180            }
181
182            &ty::Ref(r, ty, _) => {
183                self.add_region(r);
184                self.add_ty(ty);
185            }
186
187            &ty::Tuple(types) => {
188                self.add_tys(types);
189            }
190
191            &ty::FnDef(_, args) => {
192                self.add_args(args);
193            }
194
195            &ty::FnPtr(sig_tys, _) => self.bound_computation(sig_tys, |computation, sig_tys| {
196                computation.add_tys(sig_tys.inputs_and_output);
197            }),
198
199            &ty::UnsafeBinder(bound_ty) => {
200                self.bound_computation(bound_ty.into(), |computation, ty| {
201                    computation.add_ty(ty);
202                })
203            }
204        }
205    }
206
207    fn add_predicate(&mut self, binder: ty::Binder<'_, ty::PredicateKind<'_>>) {
208        self.bound_computation(binder, |computation, atom| computation.add_predicate_atom(atom));
209    }
210
211    fn add_predicate_atom(&mut self, atom: ty::PredicateKind<'_>) {
212        match atom {
213            ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_pred)) => {
214                self.add_args(trait_pred.trait_ref.args);
215            }
216            ty::PredicateKind::Clause(ty::ClauseKind::HostEffect(ty::HostEffectPredicate {
217                trait_ref,
218                constness: _,
219            })) => {
220                self.add_args(trait_ref.args);
221            }
222            ty::PredicateKind::Clause(ty::ClauseKind::RegionOutlives(ty::OutlivesPredicate(
223                a,
224                b,
225            ))) => {
226                self.add_region(a);
227                self.add_region(b);
228            }
229            ty::PredicateKind::Clause(ty::ClauseKind::TypeOutlives(ty::OutlivesPredicate(
230                ty,
231                region,
232            ))) => {
233                self.add_ty(ty);
234                self.add_region(region);
235            }
236            ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, ty)) => {
237                self.add_const(ct);
238                self.add_ty(ty);
239            }
240            ty::PredicateKind::Subtype(ty::SubtypePredicate { a_is_expected: _, a, b }) => {
241                self.add_ty(a);
242                self.add_ty(b);
243            }
244            ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => {
245                self.add_ty(a);
246                self.add_ty(b);
247            }
248            ty::PredicateKind::Clause(ty::ClauseKind::Projection(ty::ProjectionPredicate {
249                projection_term,
250                term,
251            })) => {
252                self.add_alias_term(projection_term);
253                self.add_term(term);
254            }
255            ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(arg)) => {
256                self.add_args(slice::from_ref(&arg));
257            }
258            ty::PredicateKind::DynCompatible(_def_id) => {}
259            ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(uv)) => {
260                self.add_const(uv);
261            }
262            ty::PredicateKind::ConstEquate(expected, found) => {
263                self.add_const(expected);
264                self.add_const(found);
265            }
266            ty::PredicateKind::Ambiguous => {}
267            ty::PredicateKind::NormalizesTo(ty::NormalizesTo { alias, term }) => {
268                self.add_alias_term(alias);
269                self.add_term(term);
270            }
271            ty::PredicateKind::AliasRelate(t1, t2, _) => {
272                self.add_term(t1);
273                self.add_term(t2);
274            }
275        }
276    }
277
278    fn add_ty(&mut self, ty: Ty<'_>) {
279        self.add_flags(ty.flags());
280        self.add_exclusive_binder(ty.outer_exclusive_binder());
281    }
282
283    fn add_tys(&mut self, tys: &[Ty<'_>]) {
284        for &ty in tys {
285            self.add_ty(ty);
286        }
287    }
288
289    fn add_region(&mut self, r: ty::Region<'_>) {
290        self.add_flags(r.type_flags());
291        if let ty::ReBound(debruijn, _) = *r {
292            self.add_bound_var(debruijn);
293        }
294    }
295
296    fn add_const(&mut self, c: ty::Const<'_>) {
297        self.add_flags(c.flags());
298        self.add_exclusive_binder(c.outer_exclusive_binder());
299    }
300
301    fn add_const_kind(&mut self, c: &ty::ConstKind<'_>) {
302        match *c {
303            ty::ConstKind::Unevaluated(uv) => {
304                self.add_args(uv.args);
305                self.add_flags(TypeFlags::HAS_CT_PROJECTION);
306            }
307            ty::ConstKind::Infer(infer) => match infer {
308                InferConst::Fresh(_) => self.add_flags(TypeFlags::HAS_CT_FRESH),
309                InferConst::Var(_) => self.add_flags(TypeFlags::HAS_CT_INFER),
310            },
311            ty::ConstKind::Bound(debruijn, _) => {
312                self.add_bound_var(debruijn);
313                self.add_flags(TypeFlags::HAS_CT_BOUND);
314            }
315            ty::ConstKind::Param(_) => {
316                self.add_flags(TypeFlags::HAS_CT_PARAM);
317            }
318            ty::ConstKind::Placeholder(_) => {
319                self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
320            }
321            ty::ConstKind::Value(cv) => self.add_ty(cv.ty),
322            ty::ConstKind::Expr(e) => self.add_args(e.args()),
323            ty::ConstKind::Error(_) => self.add_flags(TypeFlags::HAS_ERROR),
324        }
325    }
326
327    fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection<'_>) {
328        self.add_args(projection.args);
329        match projection.term.unpack() {
330            ty::TermKind::Ty(ty) => self.add_ty(ty),
331            ty::TermKind::Const(ct) => self.add_const(ct),
332        }
333    }
334
335    fn add_alias_ty(&mut self, alias_ty: ty::AliasTy<'_>) {
336        self.add_args(alias_ty.args);
337    }
338
339    fn add_alias_term(&mut self, alias_term: ty::AliasTerm<'_>) {
340        self.add_args(alias_term.args);
341    }
342
343    fn add_args(&mut self, args: &[GenericArg<'_>]) {
344        for kind in args {
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),
349            }
350        }
351    }
352
353    fn add_term(&mut self, term: ty::Term<'_>) {
354        match term.unpack() {
355            ty::TermKind::Ty(ty) => self.add_ty(ty),
356            ty::TermKind::Const(ct) => self.add_const(ct),
357        }
358    }
359}
rustc_middle/ty/flags.rs

rustc_middle/ty/
flags.rs
