]>
Commit | Line | Data |
---|---|---|
9fa01778 | 1 | use crate::infer::InferCtxt; |
ba9703b0 | 2 | use crate::traits; |
dfeec247 XL |
3 | use rustc_hir as hir; |
4 | use rustc_hir::def_id::DefId; | |
3dfed10e | 5 | use rustc_hir::lang_items::LangItem; |
f035d41b | 6 | use rustc_middle::ty::subst::{GenericArg, GenericArgKind, SubstsRef}; |
487cf647 | 7 | use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitable}; |
dfeec247 | 8 | use rustc_span::Span; |
e9174d1e | 9 | |
1b1a35ee | 10 | use std::iter; |
f035d41b XL |
11 | /// Returns the set of obligations needed to make `arg` well-formed. |
12 | /// If `arg` contains unresolved inference variables, this may include | |
13 | /// further WF obligations. However, if `arg` IS an unresolved | |
e9174d1e SL |
14 | /// inference variable, returns `None`, because we are not able to |
15 | /// make any progress at all. This is to prevent "livelock" where we | |
16 | /// say "$0 is WF if $0 is WF". | |
2b03887a FG |
17 | pub fn obligations<'tcx>( |
18 | infcx: &InferCtxt<'tcx>, | |
dc9dc135 XL |
19 | param_env: ty::ParamEnv<'tcx>, |
20 | body_id: hir::HirId, | |
29967ef6 | 21 | recursion_depth: usize, |
f035d41b | 22 | arg: GenericArg<'tcx>, |
dc9dc135 XL |
23 | span: Span, |
24 | ) -> Option<Vec<traits::PredicateObligation<'tcx>>> { | |
f9f354fc | 25 | // Handle the "livelock" case (see comment above) by bailing out if necessary. |
f035d41b XL |
26 | let arg = match arg.unpack() { |
27 | GenericArgKind::Type(ty) => { | |
1b1a35ee | 28 | match ty.kind() { |
f035d41b XL |
29 | ty::Infer(ty::TyVar(_)) => { |
30 | let resolved_ty = infcx.shallow_resolve(ty); | |
31 | if resolved_ty == ty { | |
32 | // No progress, bail out to prevent "livelock". | |
33 | return None; | |
f2b60f7d FG |
34 | } else { |
35 | resolved_ty | |
f035d41b | 36 | } |
f035d41b XL |
37 | } |
38 | _ => ty, | |
f9f354fc | 39 | } |
f035d41b XL |
40 | .into() |
41 | } | |
42 | GenericArgKind::Const(ct) => { | |
923072b8 | 43 | match ct.kind() { |
f2b60f7d FG |
44 | ty::ConstKind::Infer(_) => { |
45 | let resolved = infcx.shallow_resolve(ct); | |
46 | if resolved == ct { | |
f035d41b XL |
47 | // No progress. |
48 | return None; | |
f2b60f7d FG |
49 | } else { |
50 | resolved | |
f035d41b | 51 | } |
f035d41b XL |
52 | } |
53 | _ => ct, | |
54 | } | |
55 | .into() | |
f9f354fc | 56 | } |
f035d41b XL |
57 | // There is nothing we have to do for lifetimes. |
58 | GenericArgKind::Lifetime(..) => return Some(Vec::new()), | |
f9f354fc XL |
59 | }; |
60 | ||
064997fb FG |
61 | let mut wf = WfPredicates { |
62 | tcx: infcx.tcx, | |
63 | param_env, | |
64 | body_id, | |
65 | span, | |
66 | out: vec![], | |
67 | recursion_depth, | |
68 | item: None, | |
69 | }; | |
f035d41b XL |
70 | wf.compute(arg); |
71 | debug!("wf::obligations({:?}, body_id={:?}) = {:?}", arg, body_id, wf.out); | |
f9f354fc | 72 | |
064997fb | 73 | let result = wf.normalize(infcx); |
f035d41b | 74 | debug!("wf::obligations({:?}, body_id={:?}) ~~> {:?}", arg, body_id, result); |
f9f354fc | 75 | Some(result) |
e9174d1e SL |
76 | } |
77 | ||
78 | /// Returns the obligations that make this trait reference | |
79 | /// well-formed. For example, if there is a trait `Set` defined like | |
80 | /// `trait Set<K:Eq>`, then the trait reference `Foo: Set<Bar>` is WF | |
81 | /// if `Bar: Eq`. | |
2b03887a FG |
82 | pub fn trait_obligations<'tcx>( |
83 | infcx: &InferCtxt<'tcx>, | |
dc9dc135 XL |
84 | param_env: ty::ParamEnv<'tcx>, |
85 | body_id: hir::HirId, | |
064997fb | 86 | trait_pred: &ty::TraitPredicate<'tcx>, |
dc9dc135 | 87 | span: Span, |
923072b8 | 88 | item: &'tcx hir::Item<'tcx>, |
dc9dc135 | 89 | ) -> Vec<traits::PredicateObligation<'tcx>> { |
923072b8 | 90 | let mut wf = WfPredicates { |
064997fb | 91 | tcx: infcx.tcx, |
923072b8 FG |
92 | param_env, |
93 | body_id, | |
94 | span, | |
95 | out: vec![], | |
96 | recursion_depth: 0, | |
97 | item: Some(item), | |
98 | }; | |
064997fb | 99 | wf.compute_trait_pred(trait_pred, Elaborate::All); |
136023e0 | 100 | debug!(obligations = ?wf.out); |
064997fb | 101 | wf.normalize(infcx) |
e9174d1e SL |
102 | } |
103 | ||
f2b60f7d | 104 | #[instrument(skip(infcx), ret)] |
2b03887a FG |
105 | pub fn predicate_obligations<'tcx>( |
106 | infcx: &InferCtxt<'tcx>, | |
dc9dc135 XL |
107 | param_env: ty::ParamEnv<'tcx>, |
108 | body_id: hir::HirId, | |
f9f354fc | 109 | predicate: ty::Predicate<'tcx>, |
dc9dc135 XL |
110 | span: Span, |
111 | ) -> Vec<traits::PredicateObligation<'tcx>> { | |
29967ef6 | 112 | let mut wf = WfPredicates { |
064997fb | 113 | tcx: infcx.tcx, |
29967ef6 XL |
114 | param_env, |
115 | body_id, | |
116 | span, | |
117 | out: vec![], | |
118 | recursion_depth: 0, | |
119 | item: None, | |
120 | }; | |
e9174d1e | 121 | |
3dfed10e | 122 | // It's ok to skip the binder here because wf code is prepared for it |
5869c6ff | 123 | match predicate.kind().skip_binder() { |
487cf647 | 124 | ty::PredicateKind::Clause(ty::Clause::Trait(t)) => { |
064997fb | 125 | wf.compute_trait_pred(&t, Elaborate::None); |
e9174d1e | 126 | } |
487cf647 FG |
127 | ty::PredicateKind::Clause(ty::Clause::RegionOutlives(..)) => {} |
128 | ty::PredicateKind::Clause(ty::Clause::TypeOutlives(ty::OutlivesPredicate(ty, _reg))) => { | |
3dfed10e | 129 | wf.compute(ty.into()); |
e9174d1e | 130 | } |
487cf647 | 131 | ty::PredicateKind::Clause(ty::Clause::Projection(t)) => { |
e9174d1e | 132 | wf.compute_projection(t.projection_ty); |
f2b60f7d FG |
133 | wf.compute(match t.term.unpack() { |
134 | ty::TermKind::Ty(ty) => ty.into(), | |
135 | ty::TermKind::Const(c) => c.into(), | |
5099ac24 | 136 | }) |
e9174d1e | 137 | } |
5869c6ff | 138 | ty::PredicateKind::WellFormed(arg) => { |
f035d41b | 139 | wf.compute(arg); |
e9174d1e | 140 | } |
5869c6ff XL |
141 | ty::PredicateKind::ObjectSafe(_) => {} |
142 | ty::PredicateKind::ClosureKind(..) => {} | |
143 | ty::PredicateKind::Subtype(ty::SubtypePredicate { a, b, a_is_expected: _ }) => { | |
3dfed10e XL |
144 | wf.compute(a.into()); |
145 | wf.compute(b.into()); | |
cc61c64b | 146 | } |
94222f64 XL |
147 | ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => { |
148 | wf.compute(a.into()); | |
149 | wf.compute(b.into()); | |
150 | } | |
2b03887a FG |
151 | ty::PredicateKind::ConstEvaluatable(ct) => { |
152 | wf.compute(ct.into()); | |
ea8adc8c | 153 | } |
5869c6ff | 154 | ty::PredicateKind::ConstEquate(c1, c2) => { |
f035d41b XL |
155 | wf.compute(c1.into()); |
156 | wf.compute(c2.into()); | |
f9f354fc | 157 | } |
487cf647 | 158 | ty::PredicateKind::Ambiguous => {} |
5869c6ff | 159 | ty::PredicateKind::TypeWellFormedFromEnv(..) => { |
1b1a35ee XL |
160 | bug!("TypeWellFormedFromEnv is only used for Chalk") |
161 | } | |
e9174d1e SL |
162 | } |
163 | ||
064997fb | 164 | wf.normalize(infcx) |
e9174d1e SL |
165 | } |
166 | ||
064997fb FG |
167 | struct WfPredicates<'tcx> { |
168 | tcx: TyCtxt<'tcx>, | |
7cac9316 | 169 | param_env: ty::ParamEnv<'tcx>, |
9fa01778 | 170 | body_id: hir::HirId, |
e9174d1e SL |
171 | span: Span, |
172 | out: Vec<traits::PredicateObligation<'tcx>>, | |
29967ef6 | 173 | recursion_depth: usize, |
dfeec247 | 174 | item: Option<&'tcx hir::Item<'tcx>>, |
e9174d1e SL |
175 | } |
176 | ||
3b2f2976 XL |
177 | /// Controls whether we "elaborate" supertraits and so forth on the WF |
178 | /// predicates. This is a kind of hack to address #43784. The | |
179 | /// underlying problem in that issue was a trait structure like: | |
180 | /// | |
04454e1e | 181 | /// ```ignore (illustrative) |
3b2f2976 XL |
182 | /// trait Foo: Copy { } |
183 | /// trait Bar: Foo { } | |
184 | /// impl<T: Bar> Foo for T { } | |
185 | /// impl<T> Bar for T { } | |
186 | /// ``` | |
187 | /// | |
188 | /// Here, in the `Foo` impl, we will check that `T: Copy` holds -- but | |
189 | /// we decide that this is true because `T: Bar` is in the | |
190 | /// where-clauses (and we can elaborate that to include `T: | |
191 | /// Copy`). This wouldn't be a problem, except that when we check the | |
192 | /// `Bar` impl, we decide that `T: Foo` must hold because of the `Foo` | |
193 | /// impl. And so nowhere did we check that `T: Copy` holds! | |
194 | /// | |
195 | /// To resolve this, we elaborate the WF requirements that must be | |
196 | /// proven when checking impls. This means that (e.g.) the `impl Bar | |
197 | /// for T` will be forced to prove not only that `T: Foo` but also `T: | |
198 | /// Copy` (which it won't be able to do, because there is no `Copy` | |
199 | /// impl for `T`). | |
200 | #[derive(Debug, PartialEq, Eq, Copy, Clone)] | |
201 | enum Elaborate { | |
202 | All, | |
203 | None, | |
204 | } | |
205 | ||
ba9703b0 XL |
206 | fn extend_cause_with_original_assoc_item_obligation<'tcx>( |
207 | tcx: TyCtxt<'tcx>, | |
208 | trait_ref: &ty::TraitRef<'tcx>, | |
209 | item: Option<&hir::Item<'tcx>>, | |
210 | cause: &mut traits::ObligationCause<'tcx>, | |
5099ac24 | 211 | pred: ty::Predicate<'tcx>, |
ba9703b0 XL |
212 | ) { |
213 | debug!( | |
214 | "extended_cause_with_original_assoc_item_obligation {:?} {:?} {:?} {:?}", | |
215 | trait_ref, item, cause, pred | |
216 | ); | |
5099ac24 | 217 | let (items, impl_def_id) = match item { |
2b03887a FG |
218 | Some(hir::Item { kind: hir::ItemKind::Impl(impl_), owner_id, .. }) => { |
219 | (impl_.items, *owner_id) | |
220 | } | |
ba9703b0 XL |
221 | _ => return, |
222 | }; | |
223 | let fix_span = | |
c295e0f8 | 224 | |impl_item_ref: &hir::ImplItemRef| match tcx.hir().impl_item(impl_item_ref.id).kind { |
2b03887a | 225 | hir::ImplItemKind::Const(ty, _) | hir::ImplItemKind::Type(ty) => ty.span, |
ba9703b0 XL |
226 | _ => impl_item_ref.span, |
227 | }; | |
3dfed10e XL |
228 | |
229 | // It is fine to skip the binder as we don't care about regions here. | |
5869c6ff | 230 | match pred.kind().skip_binder() { |
487cf647 | 231 | ty::PredicateKind::Clause(ty::Clause::Projection(proj)) => { |
f9f354fc XL |
232 | // The obligation comes not from the current `impl` nor the `trait` being implemented, |
233 | // but rather from a "second order" obligation, where an associated type has a | |
234 | // projection coming from another associated type. See | |
235 | // `src/test/ui/associated-types/point-at-type-on-obligation-failure.rs` and | |
236 | // `traits-assoc-type-in-supertrait-bad.rs`. | |
5e7ed085 FG |
237 | if let Some(ty::Projection(projection_ty)) = proj.term.ty().map(|ty| ty.kind()) |
238 | && let Some(&impl_item_id) = | |
5099ac24 | 239 | tcx.impl_item_implementor_ids(impl_def_id).get(&projection_ty.item_def_id) |
5e7ed085 FG |
240 | && let Some(impl_item_span) = items |
241 | .iter() | |
2b03887a | 242 | .find(|item| item.id.owner_id.to_def_id() == impl_item_id) |
5e7ed085 FG |
243 | .map(fix_span) |
244 | { | |
245 | cause.span = impl_item_span; | |
ba9703b0 XL |
246 | } |
247 | } | |
487cf647 | 248 | ty::PredicateKind::Clause(ty::Clause::Trait(pred)) => { |
ba9703b0 XL |
249 | // An associated item obligation born out of the `trait` failed to be met. An example |
250 | // can be seen in `ui/associated-types/point-at-type-on-obligation-failure-2.rs`. | |
251 | debug!("extended_cause_with_original_assoc_item_obligation trait proj {:?}", pred); | |
5e7ed085 FG |
252 | if let ty::Projection(ty::ProjectionTy { item_def_id, .. }) = *pred.self_ty().kind() |
253 | && let Some(&impl_item_id) = | |
5099ac24 | 254 | tcx.impl_item_implementor_ids(impl_def_id).get(&item_def_id) |
5e7ed085 FG |
255 | && let Some(impl_item_span) = items |
256 | .iter() | |
2b03887a | 257 | .find(|item| item.id.owner_id.to_def_id() == impl_item_id) |
5e7ed085 FG |
258 | .map(fix_span) |
259 | { | |
260 | cause.span = impl_item_span; | |
ba9703b0 XL |
261 | } |
262 | } | |
263 | _ => {} | |
264 | } | |
265 | } | |
266 | ||
064997fb | 267 | impl<'tcx> WfPredicates<'tcx> { |
f9f354fc | 268 | fn tcx(&self) -> TyCtxt<'tcx> { |
064997fb | 269 | self.tcx |
f9f354fc XL |
270 | } |
271 | ||
f035d41b | 272 | fn cause(&self, code: traits::ObligationCauseCode<'tcx>) -> traits::ObligationCause<'tcx> { |
9cc50fc6 | 273 | traits::ObligationCause::new(self.span, self.body_id, code) |
e9174d1e SL |
274 | } |
275 | ||
2b03887a | 276 | fn normalize(self, infcx: &InferCtxt<'tcx>) -> Vec<traits::PredicateObligation<'tcx>> { |
064997fb | 277 | let cause = self.cause(traits::WellFormed(None)); |
7cac9316 | 278 | let param_env = self.param_env; |
74b04a01 | 279 | let mut obligations = Vec::with_capacity(self.out.len()); |
29967ef6 XL |
280 | for mut obligation in self.out { |
281 | assert!(!obligation.has_escaping_bound_vars()); | |
74b04a01 | 282 | let mut selcx = traits::SelectionContext::new(infcx); |
29967ef6 XL |
283 | // Don't normalize the whole obligation, the param env is either |
284 | // already normalized, or we're currently normalizing the | |
285 | // param_env. Either way we should only normalize the predicate. | |
286 | let normalized_predicate = traits::project::normalize_with_depth_to( | |
287 | &mut selcx, | |
288 | param_env, | |
289 | cause.clone(), | |
290 | self.recursion_depth, | |
fc512014 | 291 | obligation.predicate, |
29967ef6 XL |
292 | &mut obligations, |
293 | ); | |
294 | obligation.predicate = normalized_predicate; | |
295 | obligations.push(obligation); | |
74b04a01 XL |
296 | } |
297 | obligations | |
e9174d1e SL |
298 | } |
299 | ||
e74abb32 | 300 | /// Pushes the obligations required for `trait_ref` to be WF into `self.out`. |
064997fb FG |
301 | fn compute_trait_pred(&mut self, trait_pred: &ty::TraitPredicate<'tcx>, elaborate: Elaborate) { |
302 | let tcx = self.tcx; | |
303 | let trait_ref = &trait_pred.trait_ref; | |
e9174d1e | 304 | |
064997fb FG |
305 | // if the trait predicate is not const, the wf obligations should not be const as well. |
306 | let obligations = if trait_pred.constness == ty::BoundConstness::NotConst { | |
307 | self.nominal_obligations_without_const(trait_ref.def_id, trait_ref.substs) | |
308 | } else { | |
309 | self.nominal_obligations(trait_ref.def_id, trait_ref.substs) | |
310 | }; | |
311 | ||
312 | debug!("compute_trait_pred obligations {:?}", obligations); | |
7cac9316 | 313 | let param_env = self.param_env; |
29967ef6 | 314 | let depth = self.recursion_depth; |
3b2f2976 | 315 | |
ba9703b0 | 316 | let item = self.item; |
dfeec247 | 317 | |
923072b8 FG |
318 | let extend = |traits::PredicateObligation { predicate, mut cause, .. }| { |
319 | if let Some(parent_trait_pred) = predicate.to_opt_poly_trait_pred() { | |
320 | cause = cause.derived_cause( | |
5099ac24 | 321 | parent_trait_pred, |
923072b8 FG |
322 | traits::ObligationCauseCode::DerivedObligation, |
323 | ); | |
ba9703b0 XL |
324 | } |
325 | extend_cause_with_original_assoc_item_obligation( | |
923072b8 | 326 | tcx, trait_ref, item, &mut cause, predicate, |
ba9703b0 | 327 | ); |
487cf647 | 328 | traits::Obligation::with_depth(tcx, cause, depth, param_env, predicate) |
ba9703b0 | 329 | }; |
e74abb32 | 330 | |
3b2f2976 | 331 | if let Elaborate::All = elaborate { |
ba9703b0 XL |
332 | let implied_obligations = traits::util::elaborate_obligations(tcx, obligations); |
333 | let implied_obligations = implied_obligations.map(extend); | |
3b2f2976 | 334 | self.out.extend(implied_obligations); |
ba9703b0 XL |
335 | } else { |
336 | self.out.extend(obligations); | |
3b2f2976 XL |
337 | } |
338 | ||
f9f354fc | 339 | let tcx = self.tcx(); |
f035d41b XL |
340 | self.out.extend( |
341 | trait_ref | |
342 | .substs | |
343 | .iter() | |
3dfed10e XL |
344 | .enumerate() |
345 | .filter(|(_, arg)| { | |
f035d41b XL |
346 | matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..)) |
347 | }) | |
3dfed10e XL |
348 | .filter(|(_, arg)| !arg.has_escaping_bound_vars()) |
349 | .map(|(i, arg)| { | |
923072b8 | 350 | let mut cause = traits::ObligationCause::misc(self.span, self.body_id); |
3dfed10e XL |
351 | // The first subst is the self ty - use the correct span for it. |
352 | if i == 0 { | |
5869c6ff XL |
353 | if let Some(hir::ItemKind::Impl(hir::Impl { self_ty, .. })) = |
354 | item.map(|i| &i.kind) | |
355 | { | |
923072b8 | 356 | cause.span = self_ty.span; |
3dfed10e XL |
357 | } |
358 | } | |
29967ef6 | 359 | traits::Obligation::with_depth( |
487cf647 | 360 | tcx, |
923072b8 | 361 | cause, |
29967ef6 | 362 | depth, |
f035d41b | 363 | param_env, |
487cf647 | 364 | ty::Binder::dummy(ty::PredicateKind::WellFormed(arg)), |
f035d41b XL |
365 | ) |
366 | }), | |
367 | ); | |
e9174d1e SL |
368 | } |
369 | ||
370 | /// Pushes the obligations required for `trait_ref::Item` to be WF | |
371 | /// into `self.out`. | |
372 | fn compute_projection(&mut self, data: ty::ProjectionTy<'tcx>) { | |
29967ef6 XL |
373 | // A projection is well-formed if |
374 | // | |
375 | // (a) its predicates hold (*) | |
376 | // (b) its substs are wf | |
377 | // | |
378 | // (*) The predicates of an associated type include the predicates of | |
379 | // the trait that it's contained in. For example, given | |
380 | // | |
381 | // trait A<T>: Clone { | |
382 | // type X where T: Copy; | |
383 | // } | |
384 | // | |
385 | // The predicates of `<() as A<i32>>::X` are: | |
386 | // [ | |
387 | // `(): Sized` | |
388 | // `(): Clone` | |
389 | // `(): A<i32>` | |
390 | // `i32: Sized` | |
391 | // `i32: Clone` | |
392 | // `i32: Copy` | |
393 | // ] | |
2b03887a FG |
394 | // Projection types do not require const predicates. |
395 | let obligations = self.nominal_obligations_without_const(data.item_def_id, data.substs); | |
29967ef6 XL |
396 | self.out.extend(obligations); |
397 | ||
398 | let tcx = self.tcx(); | |
064997fb | 399 | let cause = self.cause(traits::WellFormed(None)); |
29967ef6 XL |
400 | let param_env = self.param_env; |
401 | let depth = self.recursion_depth; | |
402 | ||
403 | self.out.extend( | |
404 | data.substs | |
405 | .iter() | |
406 | .filter(|arg| { | |
407 | matches!(arg.unpack(), GenericArgKind::Type(..) | GenericArgKind::Const(..)) | |
408 | }) | |
409 | .filter(|arg| !arg.has_escaping_bound_vars()) | |
410 | .map(|arg| { | |
411 | traits::Obligation::with_depth( | |
487cf647 | 412 | tcx, |
29967ef6 XL |
413 | cause.clone(), |
414 | depth, | |
415 | param_env, | |
487cf647 | 416 | ty::Binder::dummy(ty::PredicateKind::WellFormed(arg)), |
29967ef6 XL |
417 | ) |
418 | }), | |
419 | ); | |
e9174d1e SL |
420 | } |
421 | ||
9e0c209e | 422 | fn require_sized(&mut self, subty: Ty<'tcx>, cause: traits::ObligationCauseCode<'tcx>) { |
a1dfa0c6 | 423 | if !subty.has_escaping_bound_vars() { |
a7813a04 | 424 | let cause = self.cause(cause); |
487cf647 | 425 | let trait_ref = self.tcx.at(cause.span).mk_trait_ref(LangItem::Sized, [subty]); |
29967ef6 | 426 | self.out.push(traits::Obligation::with_depth( |
487cf647 | 427 | self.tcx, |
dfeec247 | 428 | cause, |
29967ef6 | 429 | self.recursion_depth, |
dfeec247 | 430 | self.param_env, |
487cf647 | 431 | ty::Binder::dummy(trait_ref).without_const(), |
dfeec247 | 432 | )); |
a7813a04 XL |
433 | } |
434 | } | |
435 | ||
f9f354fc | 436 | /// Pushes all the predicates needed to validate that `ty` is WF into `out`. |
f2b60f7d | 437 | #[instrument(level = "debug", skip(self))] |
f035d41b | 438 | fn compute(&mut self, arg: GenericArg<'tcx>) { |
5099ac24 | 439 | let mut walker = arg.walk(); |
7cac9316 | 440 | let param_env = self.param_env; |
29967ef6 | 441 | let depth = self.recursion_depth; |
ba9703b0 | 442 | while let Some(arg) = walker.next() { |
f2b60f7d | 443 | debug!(?arg, ?self.out); |
ba9703b0 XL |
444 | let ty = match arg.unpack() { |
445 | GenericArgKind::Type(ty) => ty, | |
446 | ||
447 | // No WF constraints for lifetimes being present, any outlives | |
448 | // obligations are handled by the parent (e.g. `ty::Ref`). | |
449 | GenericArgKind::Lifetime(_) => continue, | |
450 | ||
2b03887a FG |
451 | GenericArgKind::Const(ct) => { |
452 | match ct.kind() { | |
94222f64 | 453 | ty::ConstKind::Unevaluated(uv) => { |
5099ac24 | 454 | let obligations = self.nominal_obligations(uv.def.did, uv.substs); |
f035d41b XL |
455 | self.out.extend(obligations); |
456 | ||
5099ac24 | 457 | let predicate = |
487cf647 | 458 | ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(ct)); |
064997fb | 459 | let cause = self.cause(traits::WellFormed(None)); |
29967ef6 | 460 | self.out.push(traits::Obligation::with_depth( |
487cf647 | 461 | self.tcx(), |
f035d41b | 462 | cause, |
29967ef6 | 463 | self.recursion_depth, |
f035d41b XL |
464 | self.param_env, |
465 | predicate, | |
466 | )); | |
467 | } | |
064997fb FG |
468 | ty::ConstKind::Infer(_) => { |
469 | let cause = self.cause(traits::WellFormed(None)); | |
470 | ||
471 | self.out.push(traits::Obligation::with_depth( | |
487cf647 | 472 | self.tcx(), |
064997fb FG |
473 | cause, |
474 | self.recursion_depth, | |
475 | self.param_env, | |
487cf647 | 476 | ty::Binder::dummy(ty::PredicateKind::WellFormed(ct.into())), |
064997fb | 477 | )); |
f035d41b | 478 | } |
487cf647 FG |
479 | ty::ConstKind::Expr(_) => { |
480 | // FIXME(generic_const_exprs): this doesnt verify that given `Expr(N + 1)` the | |
481 | // trait bound `typeof(N): Add<typeof(1)>` holds. This is currently unnecessary | |
482 | // as `ConstKind::Expr` is only produced via normalization of `ConstKind::Unevaluated` | |
483 | // which means that the `DefId` would have been typeck'd elsewhere. However in | |
484 | // the future we may allow directly lowering to `ConstKind::Expr` in which case | |
485 | // we would not be proving bounds we should. | |
486 | ||
487 | let predicate = | |
488 | ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(ct)); | |
489 | let cause = self.cause(traits::WellFormed(None)); | |
490 | self.out.push(traits::Obligation::with_depth( | |
491 | self.tcx(), | |
492 | cause, | |
493 | self.recursion_depth, | |
494 | self.param_env, | |
495 | predicate, | |
496 | )); | |
497 | } | |
498 | ||
f035d41b XL |
499 | ty::ConstKind::Error(_) |
500 | | ty::ConstKind::Param(_) | |
501 | | ty::ConstKind::Bound(..) | |
502 | | ty::ConstKind::Placeholder(..) => { | |
503 | // These variants are trivially WF, so nothing to do here. | |
504 | } | |
505 | ty::ConstKind::Value(..) => { | |
506 | // FIXME: Enforce that values are structurally-matchable. | |
507 | } | |
508 | } | |
509 | continue; | |
510 | } | |
ba9703b0 XL |
511 | }; |
512 | ||
f2b60f7d FG |
513 | debug!("wf bounds for ty={:?} ty.kind={:#?}", ty, ty.kind()); |
514 | ||
1b1a35ee | 515 | match *ty.kind() { |
dfeec247 XL |
516 | ty::Bool |
517 | | ty::Char | |
518 | | ty::Int(..) | |
519 | | ty::Uint(..) | |
520 | | ty::Float(..) | |
f035d41b | 521 | | ty::Error(_) |
dfeec247 XL |
522 | | ty::Str |
523 | | ty::GeneratorWitness(..) | |
524 | | ty::Never | |
525 | | ty::Param(_) | |
526 | | ty::Bound(..) | |
527 | | ty::Placeholder(..) | |
528 | | ty::Foreign(..) => { | |
e9174d1e SL |
529 | // WfScalar, WfParameter, etc |
530 | } | |
531 | ||
f9f354fc XL |
532 | // Can only infer to `ty::Int(_) | ty::Uint(_)`. |
533 | ty::Infer(ty::IntVar(_)) => {} | |
534 | ||
535 | // Can only infer to `ty::Float(_)`. | |
536 | ty::Infer(ty::FloatVar(_)) => {} | |
537 | ||
b7449926 | 538 | ty::Slice(subty) => { |
ea8adc8c XL |
539 | self.require_sized(subty, traits::SliceOrArrayElem); |
540 | } | |
541 | ||
f035d41b | 542 | ty::Array(subty, _) => { |
9e0c209e | 543 | self.require_sized(subty, traits::SliceOrArrayElem); |
f035d41b | 544 | // Note that we handle the len is implicitly checked while walking `arg`. |
a7813a04 XL |
545 | } |
546 | ||
b7449926 | 547 | ty::Tuple(ref tys) => { |
a7813a04 | 548 | if let Some((_last, rest)) = tys.split_last() { |
5e7ed085 FG |
549 | for &elem in rest { |
550 | self.require_sized(elem, traits::TupleElem); | |
e9174d1e | 551 | } |
9cc50fc6 | 552 | } |
e9174d1e SL |
553 | } |
554 | ||
b7449926 | 555 | ty::RawPtr(_) => { |
f035d41b | 556 | // Simple cases that are WF if their type args are WF. |
e9174d1e SL |
557 | } |
558 | ||
b7449926 | 559 | ty::Projection(data) => { |
f035d41b | 560 | walker.skip_current_subtree(); // Subtree handled by compute_projection. |
e9174d1e SL |
561 | self.compute_projection(data); |
562 | } | |
563 | ||
b7449926 | 564 | ty::Adt(def, substs) => { |
e9174d1e | 565 | // WfNominalType |
5e7ed085 | 566 | let obligations = self.nominal_obligations(def.did(), substs); |
e9174d1e SL |
567 | self.out.extend(obligations); |
568 | } | |
569 | ||
0731742a | 570 | ty::FnDef(did, substs) => { |
2b03887a | 571 | let obligations = self.nominal_obligations_without_const(did, substs); |
0731742a XL |
572 | self.out.extend(obligations); |
573 | } | |
574 | ||
b7449926 | 575 | ty::Ref(r, rty, _) => { |
e9174d1e | 576 | // WfReference |
a1dfa0c6 | 577 | if !r.has_escaping_bound_vars() && !rty.has_escaping_bound_vars() { |
e9174d1e | 578 | let cause = self.cause(traits::ReferenceOutlivesReferent(ty)); |
29967ef6 | 579 | self.out.push(traits::Obligation::with_depth( |
487cf647 | 580 | self.tcx(), |
dfeec247 | 581 | cause, |
29967ef6 | 582 | depth, |
dfeec247 | 583 | param_env, |
487cf647 | 584 | ty::Binder::dummy(ty::PredicateKind::Clause(ty::Clause::TypeOutlives( |
c295e0f8 | 585 | ty::OutlivesPredicate(rty, r), |
487cf647 | 586 | ))), |
dfeec247 | 587 | )); |
e9174d1e SL |
588 | } |
589 | } | |
590 | ||
064997fb | 591 | ty::Generator(did, substs, ..) => { |
ff7c6d11 XL |
592 | // Walk ALL the types in the generator: this will |
593 | // include the upvar types as well as the yield | |
594 | // type. Note that this is mildly distinct from | |
595 | // the closure case, where we have to be careful | |
596 | // about the signature of the closure. We don't | |
597 | // have the problem of implied bounds here since | |
598 | // generators don't take arguments. | |
064997fb FG |
599 | let obligations = self.nominal_obligations(did, substs); |
600 | self.out.extend(obligations); | |
ff7c6d11 XL |
601 | } |
602 | ||
923072b8 | 603 | ty::Closure(did, substs) => { |
ff7c6d11 XL |
604 | // Only check the upvar types for WF, not the rest |
605 | // of the types within. This is needed because we | |
606 | // capture the signature and it may not be WF | |
607 | // without the implied bounds. Consider a closure | |
608 | // like `|x: &'a T|` -- it may be that `T: 'a` is | |
609 | // not known to hold in the creator's context (and | |
610 | // indeed the closure may not be invoked by its | |
611 | // creator, but rather turned to someone who *can* | |
612 | // verify that). | |
613 | // | |
614 | // The special treatment of closures here really | |
615 | // ought not to be necessary either; the problem | |
616 | // is related to #25860 -- there is no way for us | |
617 | // to express a fn type complete with the implied | |
618 | // bounds that it is assuming. I think in reality | |
619 | // the WF rules around fn are a bit messed up, and | |
620 | // that is the rot problem: `fn(&'a T)` should | |
621 | // probably always be WF, because it should be | |
622 | // shorthand for something like `where(T: 'a) { | |
623 | // fn(&'a T) }`, as discussed in #25860. | |
04454e1e FG |
624 | walker.skip_current_subtree(); // subtree handled below |
625 | // FIXME(eddyb) add the type to `walker` instead of recursing. | |
626 | self.compute(substs.as_closure().tupled_upvars_ty().into()); | |
627 | // Note that we cannot skip the generic types | |
628 | // types. Normally, within the fn | |
ff7c6d11 XL |
629 | // body where they are created, the generics will |
630 | // always be WF, and outside of that fn body we | |
631 | // are not directly inspecting closure types | |
632 | // anyway, except via auto trait matching (which | |
633 | // only inspects the upvar types). | |
04454e1e FG |
634 | // But when a closure is part of a type-alias-impl-trait |
635 | // then the function that created the defining site may | |
636 | // have had more bounds available than the type alias | |
637 | // specifies. This may cause us to have a closure in the | |
638 | // hidden type that is not actually well formed and | |
639 | // can cause compiler crashes when the user abuses unsafe | |
640 | // code to procure such a closure. | |
641 | // See src/test/ui/type-alias-impl-trait/wf_check_closures.rs | |
923072b8 FG |
642 | let obligations = self.nominal_obligations(did, substs); |
643 | self.out.extend(obligations); | |
e9174d1e SL |
644 | } |
645 | ||
0731742a | 646 | ty::FnPtr(_) => { |
54a0048b | 647 | // let the loop iterate into the argument/return |
9cc50fc6 | 648 | // types appearing in the fn signature |
e9174d1e SL |
649 | } |
650 | ||
b7449926 | 651 | ty::Opaque(did, substs) => { |
064997fb FG |
652 | // All of the requirements on type parameters |
653 | // have already been checked for `impl Trait` in | |
654 | // return position. We do need to check type-alias-impl-trait though. | |
487cf647 | 655 | if self.tcx.is_type_alias_impl_trait(did) { |
8faf50e0 XL |
656 | let obligations = self.nominal_obligations(did, substs); |
657 | self.out.extend(obligations); | |
658 | } | |
5bcae85e SL |
659 | } |
660 | ||
f2b60f7d | 661 | ty::Dynamic(data, r, _) => { |
e9174d1e SL |
662 | // WfObject |
663 | // | |
664 | // Here, we defer WF checking due to higher-ranked | |
665 | // regions. This is perhaps not ideal. | |
476ff2be | 666 | self.from_object_ty(ty, data, r); |
e9174d1e SL |
667 | |
668 | // FIXME(#27579) RFC also considers adding trait | |
669 | // obligations that don't refer to Self and | |
670 | // checking those | |
671 | ||
f9f354fc | 672 | let defer_to_coercion = self.tcx().features().object_safe_for_dispatch; |
e74abb32 XL |
673 | |
674 | if !defer_to_coercion { | |
064997fb | 675 | let cause = self.cause(traits::WellFormed(None)); |
dfeec247 | 676 | let component_traits = data.auto_traits().chain(data.principal_def_id()); |
f9f354fc | 677 | let tcx = self.tcx(); |
dfeec247 | 678 | self.out.extend(component_traits.map(|did| { |
29967ef6 | 679 | traits::Obligation::with_depth( |
487cf647 | 680 | tcx, |
e74abb32 | 681 | cause.clone(), |
29967ef6 | 682 | depth, |
e74abb32 | 683 | param_env, |
487cf647 | 684 | ty::Binder::dummy(ty::PredicateKind::ObjectSafe(did)), |
dfeec247 XL |
685 | ) |
686 | })); | |
e74abb32 | 687 | } |
e9174d1e SL |
688 | } |
689 | ||
690 | // Inference variables are the complicated case, since we don't | |
691 | // know what type they are. We do two things: | |
692 | // | |
693 | // 1. Check if they have been resolved, and if so proceed with | |
694 | // THAT type. | |
f9f354fc XL |
695 | // 2. If not, we've at least simplified things (e.g., we went |
696 | // from `Vec<$0>: WF` to `$0: WF`), so we can | |
e9174d1e SL |
697 | // register a pending obligation and keep |
698 | // moving. (Goal is that an "inductive hypothesis" | |
699 | // is satisfied to ensure termination.) | |
f9f354fc XL |
700 | // See also the comment on `fn obligations`, describing "livelock" |
701 | // prevention, which happens before this can be reached. | |
b7449926 | 702 | ty::Infer(_) => { |
064997fb FG |
703 | let cause = self.cause(traits::WellFormed(None)); |
704 | self.out.push(traits::Obligation::with_depth( | |
487cf647 | 705 | self.tcx(), |
064997fb FG |
706 | cause, |
707 | self.recursion_depth, | |
708 | param_env, | |
487cf647 | 709 | ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into())), |
064997fb | 710 | )); |
e9174d1e SL |
711 | } |
712 | } | |
f2b60f7d FG |
713 | |
714 | debug!(?self.out); | |
e9174d1e | 715 | } |
e9174d1e SL |
716 | } |
717 | ||
064997fb FG |
718 | #[instrument(level = "debug", skip(self))] |
719 | fn nominal_obligations_inner( | |
dfeec247 XL |
720 | &mut self, |
721 | def_id: DefId, | |
722 | substs: SubstsRef<'tcx>, | |
064997fb | 723 | remap_constness: bool, |
dfeec247 | 724 | ) -> Vec<traits::PredicateObligation<'tcx>> { |
064997fb | 725 | let predicates = self.tcx.predicates_of(def_id); |
1b1a35ee XL |
726 | let mut origins = vec![def_id; predicates.predicates.len()]; |
727 | let mut head = predicates; | |
728 | while let Some(parent) = head.parent { | |
064997fb | 729 | head = self.tcx.predicates_of(parent); |
1b1a35ee XL |
730 | origins.extend(iter::repeat(parent).take(head.predicates.len())); |
731 | } | |
732 | ||
064997fb FG |
733 | let predicates = predicates.instantiate(self.tcx, substs); |
734 | trace!("{:#?}", predicates); | |
1b1a35ee XL |
735 | debug_assert_eq!(predicates.predicates.len(), origins.len()); |
736 | ||
cdc7bbd5 | 737 | iter::zip(iter::zip(predicates.predicates, predicates.spans), origins.into_iter().rev()) |
064997fb | 738 | .map(|((mut pred, span), origin_def_id)| { |
3c0e092e | 739 | let code = if span.is_dummy() { |
f2b60f7d | 740 | traits::ItemObligation(origin_def_id) |
3c0e092e XL |
741 | } else { |
742 | traits::BindingObligation(origin_def_id, span) | |
743 | }; | |
744 | let cause = self.cause(code); | |
064997fb FG |
745 | if remap_constness { |
746 | pred = pred.without_const(self.tcx); | |
747 | } | |
487cf647 FG |
748 | traits::Obligation::with_depth( |
749 | self.tcx, | |
750 | cause, | |
751 | self.recursion_depth, | |
752 | self.param_env, | |
753 | pred, | |
754 | ) | |
ba9703b0 | 755 | }) |
dfeec247 XL |
756 | .filter(|pred| !pred.has_escaping_bound_vars()) |
757 | .collect() | |
e9174d1e SL |
758 | } |
759 | ||
064997fb FG |
760 | fn nominal_obligations( |
761 | &mut self, | |
762 | def_id: DefId, | |
763 | substs: SubstsRef<'tcx>, | |
764 | ) -> Vec<traits::PredicateObligation<'tcx>> { | |
765 | self.nominal_obligations_inner(def_id, substs, false) | |
766 | } | |
767 | ||
768 | fn nominal_obligations_without_const( | |
769 | &mut self, | |
770 | def_id: DefId, | |
771 | substs: SubstsRef<'tcx>, | |
772 | ) -> Vec<traits::PredicateObligation<'tcx>> { | |
773 | self.nominal_obligations_inner(def_id, substs, true) | |
774 | } | |
775 | ||
dfeec247 XL |
776 | fn from_object_ty( |
777 | &mut self, | |
778 | ty: Ty<'tcx>, | |
487cf647 | 779 | data: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>, |
dfeec247 XL |
780 | region: ty::Region<'tcx>, |
781 | ) { | |
e9174d1e SL |
782 | // Imagine a type like this: |
783 | // | |
784 | // trait Foo { } | |
785 | // trait Bar<'c> : 'c { } | |
786 | // | |
787 | // &'b (Foo+'c+Bar<'d>) | |
788 | // ^ | |
789 | // | |
790 | // In this case, the following relationships must hold: | |
791 | // | |
792 | // 'b <= 'c | |
793 | // 'd <= 'c | |
794 | // | |
795 | // The first conditions is due to the normal region pointer | |
796 | // rules, which say that a reference cannot outlive its | |
797 | // referent. | |
798 | // | |
799 | // The final condition may be a bit surprising. In particular, | |
800 | // you may expect that it would have been `'c <= 'd`, since | |
801 | // usually lifetimes of outer things are conservative | |
802 | // approximations for inner things. However, it works somewhat | |
803 | // differently with trait objects: here the idea is that if the | |
804 | // user specifies a region bound (`'c`, in this case) it is the | |
805 | // "master bound" that *implies* that bounds from other traits are | |
806 | // all met. (Remember that *all bounds* in a type like | |
807 | // `Foo+Bar+Zed` must be met, not just one, hence if we write | |
808 | // `Foo<'x>+Bar<'y>`, we know that the type outlives *both* 'x and | |
809 | // 'y.) | |
810 | // | |
811 | // Note: in fact we only permit builtin traits, not `Bar<'d>`, I | |
812 | // am looking forward to the future here. | |
532ac7d7 | 813 | if !data.has_escaping_bound_vars() && !region.has_escaping_bound_vars() { |
064997fb | 814 | let implicit_bounds = object_region_bounds(self.tcx, data); |
e9174d1e | 815 | |
476ff2be | 816 | let explicit_bound = region; |
e9174d1e | 817 | |
0bf4aa26 | 818 | self.out.reserve(implicit_bounds.len()); |
e9174d1e | 819 | for implicit_bound in implicit_bounds { |
c30ab7b3 | 820 | let cause = self.cause(traits::ObjectTypeBound(ty, explicit_bound)); |
dfeec247 XL |
821 | let outlives = |
822 | ty::Binder::dummy(ty::OutlivesPredicate(explicit_bound, implicit_bound)); | |
29967ef6 | 823 | self.out.push(traits::Obligation::with_depth( |
487cf647 | 824 | self.tcx, |
dfeec247 | 825 | cause, |
29967ef6 | 826 | self.recursion_depth, |
dfeec247 | 827 | self.param_env, |
487cf647 | 828 | outlives, |
dfeec247 | 829 | )); |
e9174d1e SL |
830 | } |
831 | } | |
832 | } | |
833 | } | |
834 | ||
9fa01778 | 835 | /// Given an object type like `SomeTrait + Send`, computes the lifetime |
e9174d1e SL |
836 | /// bounds that must hold on the elided self type. These are derived |
837 | /// from the declarations of `SomeTrait`, `Send`, and friends -- if | |
838 | /// they declare `trait SomeTrait : 'static`, for example, then | |
839 | /// `'static` would appear in the list. The hard work is done by | |
dfeec247 | 840 | /// `infer::required_region_bounds`, see that for more information. |
dc9dc135 XL |
841 | pub fn object_region_bounds<'tcx>( |
842 | tcx: TyCtxt<'tcx>, | |
487cf647 | 843 | existential_predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>, |
dc9dc135 | 844 | ) -> Vec<ty::Region<'tcx>> { |
e9174d1e SL |
845 | // Since we don't actually *know* the self type for an object, |
846 | // this "open(err)" serves as a kind of dummy standin -- basically | |
0bf4aa26 | 847 | // a placeholder type. |
48663c56 | 848 | let open_ty = tcx.mk_ty_infer(ty::FreshTy(0)); |
e9174d1e | 849 | |
ba9703b0 | 850 | let predicates = existential_predicates.iter().filter_map(|predicate| { |
f035d41b | 851 | if let ty::ExistentialPredicate::Projection(_) = predicate.skip_binder() { |
ba9703b0 XL |
852 | None |
853 | } else { | |
854 | Some(predicate.with_self_ty(tcx, open_ty)) | |
60c5eb7d | 855 | } |
ba9703b0 | 856 | }); |
60c5eb7d | 857 | |
ba9703b0 | 858 | required_region_bounds(tcx, open_ty, predicates) |
60c5eb7d | 859 | } |
064997fb FG |
860 | |
861 | /// Given a set of predicates that apply to an object type, returns | |
862 | /// the region bounds that the (erased) `Self` type must | |
863 | /// outlive. Precisely *because* the `Self` type is erased, the | |
864 | /// parameter `erased_self_ty` must be supplied to indicate what type | |
865 | /// has been used to represent `Self` in the predicates | |
866 | /// themselves. This should really be a unique type; `FreshTy(0)` is a | |
867 | /// popular choice. | |
868 | /// | |
869 | /// N.B., in some cases, particularly around higher-ranked bounds, | |
870 | /// this function returns a kind of conservative approximation. | |
871 | /// That is, all regions returned by this function are definitely | |
872 | /// required, but there may be other region bounds that are not | |
873 | /// returned, as well as requirements like `for<'a> T: 'a`. | |
874 | /// | |
875 | /// Requires that trait definitions have been processed so that we can | |
876 | /// elaborate predicates and walk supertraits. | |
f2b60f7d | 877 | #[instrument(skip(tcx, predicates), level = "debug", ret)] |
064997fb FG |
878 | pub(crate) fn required_region_bounds<'tcx>( |
879 | tcx: TyCtxt<'tcx>, | |
880 | erased_self_ty: Ty<'tcx>, | |
881 | predicates: impl Iterator<Item = ty::Predicate<'tcx>>, | |
882 | ) -> Vec<ty::Region<'tcx>> { | |
883 | assert!(!erased_self_ty.has_escaping_bound_vars()); | |
884 | ||
885 | traits::elaborate_predicates(tcx, predicates) | |
886 | .filter_map(|obligation| { | |
887 | debug!(?obligation); | |
888 | match obligation.predicate.kind().skip_binder() { | |
487cf647 FG |
889 | ty::PredicateKind::Clause(ty::Clause::Projection(..)) |
890 | | ty::PredicateKind::Clause(ty::Clause::Trait(..)) | |
064997fb FG |
891 | | ty::PredicateKind::Subtype(..) |
892 | | ty::PredicateKind::Coerce(..) | |
893 | | ty::PredicateKind::WellFormed(..) | |
894 | | ty::PredicateKind::ObjectSafe(..) | |
895 | | ty::PredicateKind::ClosureKind(..) | |
487cf647 | 896 | | ty::PredicateKind::Clause(ty::Clause::RegionOutlives(..)) |
064997fb FG |
897 | | ty::PredicateKind::ConstEvaluatable(..) |
898 | | ty::PredicateKind::ConstEquate(..) | |
487cf647 | 899 | | ty::PredicateKind::Ambiguous |
064997fb | 900 | | ty::PredicateKind::TypeWellFormedFromEnv(..) => None, |
487cf647 FG |
901 | ty::PredicateKind::Clause(ty::Clause::TypeOutlives(ty::OutlivesPredicate( |
902 | ref t, | |
903 | ref r, | |
904 | ))) => { | |
064997fb FG |
905 | // Search for a bound of the form `erased_self_ty |
906 | // : 'a`, but be wary of something like `for<'a> | |
907 | // erased_self_ty : 'a` (we interpret a | |
908 | // higher-ranked bound like that as 'static, | |
909 | // though at present the code in `fulfill.rs` | |
910 | // considers such bounds to be unsatisfiable, so | |
911 | // it's kind of a moot point since you could never | |
912 | // construct such an object, but this seems | |
913 | // correct even if that code changes). | |
914 | if t == &erased_self_ty && !r.has_escaping_bound_vars() { | |
915 | Some(*r) | |
916 | } else { | |
917 | None | |
918 | } | |
919 | } | |
920 | } | |
921 | }) | |
922 | .collect() | |
923 | } |