1use rustc_data_structures::fx::FxIndexSet;
4use rustc_errors::{Applicability, Diag, ErrorGuaranteed, MultiSpan};
5use rustc_hir as hir;
6use rustc_hir::GenericBound::Trait;
7use rustc_hir::QPath::Resolved;
8use rustc_hir::WherePredicateKind::BoundPredicate;
9use rustc_hir::def::Res::Def;
10use rustc_hir::def_id::DefId;
11use rustc_hir::intravisit::VisitorExt;
12use rustc_hir::{PolyTraitRef, TyKind, WhereBoundPredicate};
13use rustc_infer::infer::{NllRegionVariableOrigin, RelateParamBound};
14use rustc_middle::bug;
15use rustc_middle::hir::place::PlaceBase;
16use rustc_middle::mir::{AnnotationSource, ConstraintCategory, ReturnConstraint};
17use rustc_middle::ty::{
18 self, GenericArgs, Region, RegionVid, Ty, TyCtxt, TypeFoldable, TypeVisitor, fold_regions,
19};
20use rustc_span::{Ident, Span, kw};
21use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
22use rustc_trait_selection::error_reporting::infer::nice_region_error::{
23 self, HirTraitObjectVisitor, NiceRegionError, TraitObjectVisitor, find_anon_type,
24 find_param_with_region, suggest_adding_lifetime_params,
25};
26use rustc_trait_selection::error_reporting::infer::region::unexpected_hidden_region_diagnostic;
27use rustc_trait_selection::infer::InferCtxtExt;
28use rustc_trait_selection::traits::{Obligation, ObligationCtxt};
29use tracing::{debug, instrument, trace};
30
31use super::{OutlivesSuggestionBuilder, RegionName, RegionNameSource};
32use crate::nll::ConstraintDescription;
33use crate::region_infer::values::RegionElement;
34use crate::region_infer::{BlameConstraint, TypeTest};
35use crate::session_diagnostics::{
36 FnMutError, FnMutReturnTypeErr, GenericDoesNotLiveLongEnough, LifetimeOutliveErr,
37 LifetimeReturnCategoryErr, RequireStaticErr, VarHereDenote,
38};
39use crate::universal_regions::DefiningTy;
40use crate::{MirBorrowckCtxt, borrowck_errors, fluent_generated as fluent};
41
42impl<'tcx> ConstraintDescription for ConstraintCategory<'tcx> {
43 fn description(&self) -> &'static str {
44 match self {
46 ConstraintCategory::Assignment => "assignment ",
47 ConstraintCategory::Return(_) => "returning this value ",
48 ConstraintCategory::Yield => "yielding this value ",
49 ConstraintCategory::UseAsConst => "using this value as a constant ",
50 ConstraintCategory::UseAsStatic => "using this value as a static ",
51 ConstraintCategory::Cast { is_implicit_coercion: false, .. } => "cast ",
52 ConstraintCategory::Cast { is_implicit_coercion: true, .. } => "coercion ",
53 ConstraintCategory::CallArgument(_) => "argument ",
54 ConstraintCategory::TypeAnnotation(AnnotationSource::GenericArg) => "generic argument ",
55 ConstraintCategory::TypeAnnotation(_) => "type annotation ",
56 ConstraintCategory::SizedBound => "proving this value is `Sized` ",
57 ConstraintCategory::CopyBound => "copying this value ",
58 ConstraintCategory::OpaqueType => "opaque type ",
59 ConstraintCategory::ClosureUpvar(_) => "closure capture ",
60 ConstraintCategory::Usage => "this usage ",
61 ConstraintCategory::Predicate(_)
62 | ConstraintCategory::Boring
63 | ConstraintCategory::BoringNoLocation
64 | ConstraintCategory::Internal
65 | ConstraintCategory::IllegalUniverse => "",
66 }
67 }
68}
69
70pub(crate) struct RegionErrors<'tcx>(Vec<(RegionErrorKind<'tcx>, ErrorGuaranteed)>, TyCtxt<'tcx>);
76
77impl<'tcx> RegionErrors<'tcx> {
78 pub(crate) fn new(tcx: TyCtxt<'tcx>) -> Self {
79 Self(vec![], tcx)
80 }
81 #[track_caller]
82 pub(crate) fn push(&mut self, val: impl Into<RegionErrorKind<'tcx>>) {
83 let val = val.into();
84 let guar = self.1.sess.dcx().delayed_bug(format!("{val:?}"));
85 self.0.push((val, guar));
86 }
87 pub(crate) fn is_empty(&self) -> bool {
88 self.0.is_empty()
89 }
90 pub(crate) fn into_iter(
91 self,
92 ) -> impl Iterator<Item = (RegionErrorKind<'tcx>, ErrorGuaranteed)> {
93 self.0.into_iter()
94 }
95 pub(crate) fn has_errors(&self) -> Option<ErrorGuaranteed> {
96 self.0.get(0).map(|x| x.1)
97 }
98}
99
100impl std::fmt::Debug for RegionErrors<'_> {
101 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
102 f.debug_tuple("RegionErrors").field(&self.0).finish()
103 }
104}
105
106#[derive(Clone, Debug)]
107pub(crate) enum RegionErrorKind<'tcx> {
108 TypeTestError { type_test: TypeTest<'tcx> },
110
111 UnexpectedHiddenRegion {
113 span: Span,
115 hidden_ty: Ty<'tcx>,
117 key: ty::OpaqueTypeKey<'tcx>,
119 member_region: ty::Region<'tcx>,
121 },
122
123 BoundUniversalRegionError {
125 longer_fr: RegionVid,
127 error_element: RegionElement,
129 placeholder: ty::PlaceholderRegion,
131 },
132
133 RegionError {
135 fr_origin: NllRegionVariableOrigin,
137 longer_fr: RegionVid,
139 shorter_fr: RegionVid,
141 is_reported: bool,
144 },
145}
146
147#[derive(Clone, Debug)]
149pub(crate) struct ErrorConstraintInfo<'tcx> {
150 pub(super) fr: RegionVid,
152 pub(super) outlived_fr: RegionVid,
153
154 pub(super) category: ConstraintCategory<'tcx>,
156 pub(super) span: Span,
157}
158
159impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
160 pub(super) fn to_error_region(&self, r: RegionVid) -> Option<ty::Region<'tcx>> {
167 self.to_error_region_vid(r).and_then(|r| self.regioncx.region_definition(r).external_name)
168 }
169
170 pub(super) fn to_error_region_vid(&self, r: RegionVid) -> Option<RegionVid> {
173 if self.regioncx.universal_regions().is_universal_region(r) {
174 Some(r)
175 } else {
176 let upper_bound = self.regioncx.approx_universal_upper_bound(r);
179
180 if self.regioncx.upper_bound_in_region_scc(r, upper_bound) {
181 self.to_error_region_vid(upper_bound)
182 } else {
183 None
184 }
185 }
186 }
187
188 fn name_regions<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T
190 where
191 T: TypeFoldable<TyCtxt<'tcx>>,
192 {
193 fold_regions(tcx, ty, |region, _| match *region {
194 ty::ReVar(vid) => self.to_error_region(vid).unwrap_or(region),
195 _ => region,
196 })
197 }
198
199 fn is_closure_fn_mut(&self, fr: RegionVid) -> bool {
201 if let Some(ty::ReLateParam(late_param)) = self.to_error_region(fr).as_deref()
202 && let ty::LateParamRegionKind::ClosureEnv = late_param.kind
203 && let DefiningTy::Closure(_, args) = self.regioncx.universal_regions().defining_ty
204 {
205 return args.as_closure().kind() == ty::ClosureKind::FnMut;
206 }
207
208 false
209 }
210
211 #[allow(rustc::diagnostic_outside_of_impl)]
215 fn suggest_static_lifetime_for_gat_from_hrtb(
216 &self,
217 diag: &mut Diag<'_>,
218 lower_bound: RegionVid,
219 ) {
220 let mut suggestions = vec![];
221 let tcx = self.infcx.tcx;
222
223 let gat_id_and_generics = self
225 .regioncx
226 .placeholders_contained_in(lower_bound)
227 .map(|placeholder| {
228 if let Some(id) = placeholder.bound.kind.get_id()
229 && let Some(placeholder_id) = id.as_local()
230 && let gat_hir_id = tcx.local_def_id_to_hir_id(placeholder_id)
231 && let Some(generics_impl) =
232 tcx.parent_hir_node(tcx.parent_hir_id(gat_hir_id)).generics()
233 {
234 Some((gat_hir_id, generics_impl))
235 } else {
236 None
237 }
238 })
239 .collect::<Vec<_>>();
240 debug!(?gat_id_and_generics);
241
242 let mut hrtb_bounds = vec![];
244 gat_id_and_generics.iter().flatten().for_each(|(gat_hir_id, generics)| {
245 for pred in generics.predicates {
246 let BoundPredicate(WhereBoundPredicate { bound_generic_params, bounds, .. }) =
247 pred.kind
248 else {
249 continue;
250 };
251 if bound_generic_params
252 .iter()
253 .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == *gat_hir_id)
254 .is_some()
255 {
256 for bound in *bounds {
257 hrtb_bounds.push(bound);
258 }
259 }
260 }
261 });
262 debug!(?hrtb_bounds);
263
264 hrtb_bounds.iter().for_each(|bound| {
265 let Trait(PolyTraitRef { trait_ref, span: trait_span, .. }) = bound else {
266 return;
267 };
268 diag.span_note(*trait_span, fluent::borrowck_limitations_implies_static);
269 let Some(generics_fn) = tcx.hir_get_generics(self.body.source.def_id().expect_local())
270 else {
271 return;
272 };
273 let Def(_, trait_res_defid) = trait_ref.path.res else {
274 return;
275 };
276 debug!(?generics_fn);
277 generics_fn.predicates.iter().for_each(|predicate| {
278 let BoundPredicate(WhereBoundPredicate { bounded_ty, bounds, .. }) = predicate.kind
279 else {
280 return;
281 };
282 bounds.iter().for_each(|bd| {
283 if let Trait(PolyTraitRef { trait_ref: tr_ref, .. }) = bd
284 && let Def(_, res_defid) = tr_ref.path.res
285 && res_defid == trait_res_defid && let TyKind::Path(Resolved(_, path)) = bounded_ty.kind
287 && let Def(_, defid) = path.res
288 && generics_fn.params
289 .iter()
290 .rfind(|param| param.def_id.to_def_id() == defid)
291 .is_some()
292 {
293 suggestions.push((predicate.span.shrink_to_hi(), " + 'static".to_string()));
294 }
295 });
296 });
297 });
298 if suggestions.len() > 0 {
299 suggestions.dedup();
300 diag.multipart_suggestion_verbose(
301 fluent::borrowck_restrict_to_static,
302 suggestions,
303 Applicability::MaybeIncorrect,
304 );
305 }
306 }
307
308 pub(crate) fn report_region_errors(&mut self, nll_errors: RegionErrors<'tcx>) {
310 let mut outlives_suggestion = OutlivesSuggestionBuilder::default();
314 let mut last_unexpected_hidden_region: Option<(Span, Ty<'_>, ty::OpaqueTypeKey<'tcx>)> =
315 None;
316
317 for (nll_error, _) in nll_errors.into_iter() {
318 match nll_error {
319 RegionErrorKind::TypeTestError { type_test } => {
320 let lower_bound_region = self.to_error_region(type_test.lower_bound);
323
324 let type_test_span = type_test.span;
325
326 if let Some(lower_bound_region) = lower_bound_region {
327 let generic_ty = self.name_regions(
328 self.infcx.tcx,
329 type_test.generic_kind.to_ty(self.infcx.tcx),
330 );
331 let origin = RelateParamBound(type_test_span, generic_ty, None);
332 self.buffer_error(self.infcx.err_ctxt().construct_generic_bound_failure(
333 self.body.source.def_id().expect_local(),
334 type_test_span,
335 Some(origin),
336 self.name_regions(self.infcx.tcx, type_test.generic_kind),
337 lower_bound_region,
338 ));
339 } else {
340 let mut diag = self.dcx().create_err(GenericDoesNotLiveLongEnough {
350 kind: type_test.generic_kind.to_string(),
351 span: type_test_span,
352 });
353
354 self.suggest_static_lifetime_for_gat_from_hrtb(
358 &mut diag,
359 type_test.lower_bound,
360 );
361
362 self.buffer_error(diag);
363 }
364 }
365
366 RegionErrorKind::UnexpectedHiddenRegion { span, hidden_ty, key, member_region } => {
367 let named_ty =
368 self.regioncx.name_regions_for_member_constraint(self.infcx.tcx, hidden_ty);
369 let named_key =
370 self.regioncx.name_regions_for_member_constraint(self.infcx.tcx, key);
371 let named_region = self
372 .regioncx
373 .name_regions_for_member_constraint(self.infcx.tcx, member_region);
374 let diag = unexpected_hidden_region_diagnostic(
375 self.infcx,
376 self.mir_def_id(),
377 span,
378 named_ty,
379 named_region,
380 named_key,
381 );
382 if last_unexpected_hidden_region != Some((span, named_ty, named_key)) {
383 self.buffer_error(diag);
384 last_unexpected_hidden_region = Some((span, named_ty, named_key));
385 } else {
386 diag.delay_as_bug();
387 }
388 }
389
390 RegionErrorKind::BoundUniversalRegionError {
391 longer_fr,
392 placeholder,
393 error_element,
394 } => {
395 let error_vid = self.regioncx.region_from_element(longer_fr, &error_element);
396
397 let (_, cause) = self.regioncx.find_outlives_blame_span(
399 longer_fr,
400 NllRegionVariableOrigin::Placeholder(placeholder),
401 error_vid,
402 );
403
404 let universe = placeholder.universe;
405 let universe_info = self.regioncx.universe_info(universe);
406
407 universe_info.report_error(self, placeholder, error_element, cause);
408 }
409
410 RegionErrorKind::RegionError { fr_origin, longer_fr, shorter_fr, is_reported } => {
411 if is_reported {
412 self.report_region_error(
413 longer_fr,
414 fr_origin,
415 shorter_fr,
416 &mut outlives_suggestion,
417 );
418 } else {
419 debug!(
426 "Unreported region error: can't prove that {:?}: {:?}",
427 longer_fr, shorter_fr
428 );
429 }
430 }
431 }
432 }
433
434 outlives_suggestion.add_suggestion(self);
436 }
437
438 #[allow(rustc::diagnostic_outside_of_impl)]
448 #[allow(rustc::untranslatable_diagnostic)]
449 pub(crate) fn report_region_error(
450 &mut self,
451 fr: RegionVid,
452 fr_origin: NllRegionVariableOrigin,
453 outlived_fr: RegionVid,
454 outlives_suggestion: &mut OutlivesSuggestionBuilder,
455 ) {
456 debug!("report_region_error(fr={:?}, outlived_fr={:?})", fr, outlived_fr);
457
458 let (blame_constraint, path) = self.regioncx.best_blame_constraint(fr, fr_origin, |r| {
459 self.regioncx.provides_universal_region(r, fr, outlived_fr)
460 });
461 let BlameConstraint { category, cause, variance_info, .. } = blame_constraint;
462
463 debug!("report_region_error: category={:?} {:?} {:?}", category, cause, variance_info);
464
465 if let (Some(f), Some(o)) = (self.to_error_region(fr), self.to_error_region(outlived_fr)) {
467 let infer_err = self.infcx.err_ctxt();
468 let nice =
469 NiceRegionError::new_from_span(&infer_err, self.mir_def_id(), cause.span, o, f);
470 if let Some(diag) = nice.try_report_from_nll() {
471 self.buffer_error(diag);
472 return;
473 }
474 }
475
476 let (fr_is_local, outlived_fr_is_local): (bool, bool) = (
477 self.regioncx.universal_regions().is_local_free_region(fr),
478 self.regioncx.universal_regions().is_local_free_region(outlived_fr),
479 );
480
481 debug!(
482 "report_region_error: fr_is_local={:?} outlived_fr_is_local={:?} category={:?}",
483 fr_is_local, outlived_fr_is_local, category
484 );
485
486 let errci = ErrorConstraintInfo { fr, outlived_fr, category, span: cause.span };
487
488 let mut diag = match (category, fr_is_local, outlived_fr_is_local) {
489 (ConstraintCategory::Return(kind), true, false) if self.is_closure_fn_mut(fr) => {
490 self.report_fnmut_error(&errci, kind)
491 }
492 (ConstraintCategory::Assignment, true, false)
493 | (ConstraintCategory::CallArgument(_), true, false) => {
494 let mut db = self.report_escaping_data_error(&errci);
495
496 outlives_suggestion.intermediate_suggestion(self, &errci, &mut db);
497 outlives_suggestion.collect_constraint(fr, outlived_fr);
498
499 db
500 }
501 _ => {
502 let mut db = self.report_general_error(&errci);
503
504 outlives_suggestion.intermediate_suggestion(self, &errci, &mut db);
505 outlives_suggestion.collect_constraint(fr, outlived_fr);
506
507 db
508 }
509 };
510
511 match variance_info {
512 ty::VarianceDiagInfo::None => {}
513 ty::VarianceDiagInfo::Invariant { ty, param_index } => {
514 let (desc, note) = match ty.kind() {
515 ty::RawPtr(ty, mutbl) => {
516 assert_eq!(*mutbl, rustc_hir::Mutability::Mut);
517 (
518 format!("a mutable pointer to `{}`", ty),
519 "mutable pointers are invariant over their type parameter".to_string(),
520 )
521 }
522 ty::Ref(_, inner_ty, mutbl) => {
523 assert_eq!(*mutbl, rustc_hir::Mutability::Mut);
524 (
525 format!("a mutable reference to `{inner_ty}`"),
526 "mutable references are invariant over their type parameter"
527 .to_string(),
528 )
529 }
530 ty::Adt(adt, args) => {
531 let generic_arg = args[param_index as usize];
532 let identity_args =
533 GenericArgs::identity_for_item(self.infcx.tcx, adt.did());
534 let base_ty = Ty::new_adt(self.infcx.tcx, *adt, identity_args);
535 let base_generic_arg = identity_args[param_index as usize];
536 let adt_desc = adt.descr();
537
538 let desc = format!(
539 "the type `{ty}`, which makes the generic argument `{generic_arg}` invariant"
540 );
541 let note = format!(
542 "the {adt_desc} `{base_ty}` is invariant over the parameter `{base_generic_arg}`"
543 );
544 (desc, note)
545 }
546 ty::FnDef(def_id, _) => {
547 let name = self.infcx.tcx.item_name(*def_id);
548 let identity_args = GenericArgs::identity_for_item(self.infcx.tcx, *def_id);
549 let desc = format!("a function pointer to `{name}`");
550 let note = format!(
551 "the function `{name}` is invariant over the parameter `{}`",
552 identity_args[param_index as usize]
553 );
554 (desc, note)
555 }
556 _ => panic!("Unexpected type {ty:?}"),
557 };
558 diag.note(format!("requirement occurs because of {desc}",));
559 diag.note(note);
560 diag.help("see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance");
561 }
562 }
563
564 self.add_placeholder_from_predicate_note(&mut diag, &path);
565 self.add_sized_or_copy_bound_info(&mut diag, category, &path);
566
567 self.buffer_error(diag);
568 }
569
570 #[allow(rustc::diagnostic_outside_of_impl)] fn report_fnmut_error(
588 &self,
589 errci: &ErrorConstraintInfo<'tcx>,
590 kind: ReturnConstraint,
591 ) -> Diag<'infcx> {
592 let ErrorConstraintInfo { outlived_fr, span, .. } = errci;
593
594 let mut output_ty = self.regioncx.universal_regions().unnormalized_output_ty;
595 if let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = *output_ty.kind() {
596 output_ty = self.infcx.tcx.type_of(def_id).instantiate_identity()
597 };
598
599 debug!("report_fnmut_error: output_ty={:?}", output_ty);
600
601 let err = FnMutError {
602 span: *span,
603 ty_err: match output_ty.kind() {
604 ty::Coroutine(def, ..) if self.infcx.tcx.coroutine_is_async(*def) => {
605 FnMutReturnTypeErr::ReturnAsyncBlock { span: *span }
606 }
607 _ if output_ty.contains_closure() => {
608 FnMutReturnTypeErr::ReturnClosure { span: *span }
609 }
610 _ => FnMutReturnTypeErr::ReturnRef { span: *span },
611 },
612 };
613
614 let mut diag = self.dcx().create_err(err);
615
616 if let ReturnConstraint::ClosureUpvar(upvar_field) = kind {
617 let def_id = match self.regioncx.universal_regions().defining_ty {
618 DefiningTy::Closure(def_id, _) => def_id,
619 ty => bug!("unexpected DefiningTy {:?}", ty),
620 };
621
622 let captured_place = &self.upvars[upvar_field.index()].place;
623 let defined_hir = match captured_place.base {
624 PlaceBase::Local(hirid) => Some(hirid),
625 PlaceBase::Upvar(upvar) => Some(upvar.var_path.hir_id),
626 _ => None,
627 };
628
629 if let Some(def_hir) = defined_hir {
630 let upvars_map = self.infcx.tcx.upvars_mentioned(def_id).unwrap();
631 let upvar_def_span = self.infcx.tcx.hir().span(def_hir);
632 let upvar_span = upvars_map.get(&def_hir).unwrap().span;
633 diag.subdiagnostic(VarHereDenote::Defined { span: upvar_def_span });
634 diag.subdiagnostic(VarHereDenote::Captured { span: upvar_span });
635 }
636 }
637
638 if let Some(fr_span) = self.give_region_a_name(*outlived_fr).unwrap().span() {
639 diag.subdiagnostic(VarHereDenote::FnMutInferred { span: fr_span });
640 }
641
642 self.suggest_move_on_borrowing_closure(&mut diag);
643
644 diag
645 }
646
647 #[instrument(level = "debug", skip(self))]
660 fn report_escaping_data_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'infcx> {
661 let ErrorConstraintInfo { span, category, .. } = errci;
662
663 let fr_name_and_span = self.regioncx.get_var_name_and_span_for_region(
664 self.infcx.tcx,
665 self.body,
666 &self.local_names,
667 &self.upvars,
668 errci.fr,
669 );
670 let outlived_fr_name_and_span = self.regioncx.get_var_name_and_span_for_region(
671 self.infcx.tcx,
672 self.body,
673 &self.local_names,
674 &self.upvars,
675 errci.outlived_fr,
676 );
677
678 let escapes_from =
679 self.infcx.tcx.def_descr(self.regioncx.universal_regions().defining_ty.def_id());
680
681 if (fr_name_and_span.is_none() && outlived_fr_name_and_span.is_none())
684 || (*category == ConstraintCategory::Assignment
685 && self.regioncx.universal_regions().defining_ty.is_fn_def())
686 || self.regioncx.universal_regions().defining_ty.is_const()
687 {
688 return self.report_general_error(errci);
689 }
690
691 let mut diag =
692 borrowck_errors::borrowed_data_escapes_closure(self.infcx.tcx, *span, escapes_from);
693
694 if let Some((Some(outlived_fr_name), outlived_fr_span)) = outlived_fr_name_and_span {
695 #[allow(rustc::diagnostic_outside_of_impl)]
697 #[allow(rustc::untranslatable_diagnostic)]
698 diag.span_label(
699 outlived_fr_span,
700 format!("`{outlived_fr_name}` declared here, outside of the {escapes_from} body",),
701 );
702 }
703
704 #[allow(rustc::diagnostic_outside_of_impl)]
706 #[allow(rustc::untranslatable_diagnostic)]
707 if let Some((Some(fr_name), fr_span)) = fr_name_and_span {
708 diag.span_label(
709 fr_span,
710 format!(
711 "`{fr_name}` is a reference that is only valid in the {escapes_from} body",
712 ),
713 );
714
715 diag.span_label(*span, format!("`{fr_name}` escapes the {escapes_from} body here"));
716 }
717
718 match (self.to_error_region(errci.fr), self.to_error_region(errci.outlived_fr)) {
722 (Some(f), Some(o)) => {
723 self.maybe_suggest_constrain_dyn_trait_impl(&mut diag, f, o, category);
724
725 let fr_region_name = self.give_region_a_name(errci.fr).unwrap();
726 fr_region_name.highlight_region_name(&mut diag);
727 let outlived_fr_region_name = self.give_region_a_name(errci.outlived_fr).unwrap();
728 outlived_fr_region_name.highlight_region_name(&mut diag);
729
730 #[allow(rustc::diagnostic_outside_of_impl)]
732 #[allow(rustc::untranslatable_diagnostic)]
733 diag.span_label(
734 *span,
735 format!(
736 "{}requires that `{}` must outlive `{}`",
737 category.description(),
738 fr_region_name,
739 outlived_fr_region_name,
740 ),
741 );
742 }
743 _ => {}
744 }
745
746 diag
747 }
748
749 #[allow(rustc::diagnostic_outside_of_impl)] fn report_general_error(&self, errci: &ErrorConstraintInfo<'tcx>) -> Diag<'infcx> {
766 let ErrorConstraintInfo { fr, outlived_fr, span, category, .. } = errci;
767
768 let mir_def_name = self.infcx.tcx.def_descr(self.mir_def_id().to_def_id());
769
770 let err = LifetimeOutliveErr { span: *span };
771 let mut diag = self.dcx().create_err(err);
772
773 let fr_name = self.give_region_a_name(*fr).unwrap_or(RegionName {
778 name: kw::UnderscoreLifetime,
779 source: RegionNameSource::Static,
780 });
781 fr_name.highlight_region_name(&mut diag);
782 let outlived_fr_name = self.give_region_a_name(*outlived_fr).unwrap();
783 outlived_fr_name.highlight_region_name(&mut diag);
784
785 let err_category = if matches!(category, ConstraintCategory::Return(_))
786 && self.regioncx.universal_regions().is_local_free_region(*outlived_fr)
787 {
788 LifetimeReturnCategoryErr::WrongReturn {
789 span: *span,
790 mir_def_name,
791 outlived_fr_name,
792 fr_name: &fr_name,
793 }
794 } else {
795 LifetimeReturnCategoryErr::ShortReturn {
796 span: *span,
797 category_desc: category.description(),
798 free_region_name: &fr_name,
799 outlived_fr_name,
800 }
801 };
802
803 diag.subdiagnostic(err_category);
804
805 self.add_static_impl_trait_suggestion(&mut diag, *fr, fr_name, *outlived_fr);
806 self.suggest_adding_lifetime_params(&mut diag, *fr, *outlived_fr);
807 self.suggest_move_on_borrowing_closure(&mut diag);
808 self.suggest_deref_closure_return(&mut diag);
809
810 diag
811 }
812
813 #[allow(rustc::diagnostic_outside_of_impl)]
823 #[allow(rustc::untranslatable_diagnostic)] fn add_static_impl_trait_suggestion(
825 &self,
826 diag: &mut Diag<'_>,
827 fr: RegionVid,
828 fr_name: RegionName,
830 outlived_fr: RegionVid,
831 ) {
832 if let (Some(f), Some(outlived_f)) =
833 (self.to_error_region(fr), self.to_error_region(outlived_fr))
834 {
835 if *outlived_f != ty::ReStatic {
836 return;
837 }
838 let suitable_region = self.infcx.tcx.is_suitable_region(self.mir_def_id(), f);
839 let Some(suitable_region) = suitable_region else {
840 return;
841 };
842
843 let fn_returns = self.infcx.tcx.return_type_impl_or_dyn_traits(suitable_region.scope);
844
845 let param = if let Some(param) =
846 find_param_with_region(self.infcx.tcx, self.mir_def_id(), f, outlived_f)
847 {
848 param
849 } else {
850 return;
851 };
852
853 let lifetime = if f.has_name() { fr_name.name } else { kw::UnderscoreLifetime };
854
855 let arg = match param.param.pat.simple_ident() {
856 Some(simple_ident) => format!("argument `{simple_ident}`"),
857 None => "the argument".to_string(),
858 };
859 let captures = format!("captures data from {arg}");
860
861 if !fn_returns.is_empty() {
862 nice_region_error::suggest_new_region_bound(
863 self.infcx.tcx,
864 diag,
865 fn_returns,
866 lifetime.to_string(),
867 Some(arg),
868 captures,
869 Some((param.param_ty_span, param.param_ty.to_string())),
870 Some(suitable_region.scope),
871 );
872 return;
873 }
874
875 let Some((alias_tys, alias_span, lt_addition_span)) = self
876 .infcx
877 .tcx
878 .return_type_impl_or_dyn_traits_with_type_alias(suitable_region.scope)
879 else {
880 return;
881 };
882
883 let mut spans_suggs: Vec<_> = Vec::new();
885 for alias_ty in alias_tys {
886 if alias_ty.span.desugaring_kind().is_some() {
887 }
889 if let TyKind::TraitObject(_, lt) = alias_ty.kind {
890 if lt.ident.name == kw::Empty {
891 spans_suggs.push((lt.ident.span.shrink_to_hi(), " + 'a".to_string()));
892 } else {
893 spans_suggs.push((lt.ident.span, "'a".to_string()));
894 }
895 }
896 }
897
898 if let Some(lt_addition_span) = lt_addition_span {
899 spans_suggs.push((lt_addition_span, "'a, ".to_string()));
900 } else {
901 spans_suggs.push((alias_span.shrink_to_hi(), "<'a>".to_string()));
902 }
903
904 diag.multipart_suggestion_verbose(
905 format!(
906 "to declare that the trait object {captures}, you can add a lifetime parameter `'a` in the type alias"
907 ),
908 spans_suggs,
909 Applicability::MaybeIncorrect,
910 );
911 }
912 }
913
914 fn maybe_suggest_constrain_dyn_trait_impl(
915 &self,
916 diag: &mut Diag<'_>,
917 f: Region<'tcx>,
918 o: Region<'tcx>,
919 category: &ConstraintCategory<'tcx>,
920 ) {
921 if !o.is_static() {
922 return;
923 }
924
925 let tcx = self.infcx.tcx;
926
927 let instance = if let ConstraintCategory::CallArgument(Some(func_ty)) = category {
928 let (fn_did, args) = match func_ty.kind() {
929 ty::FnDef(fn_did, args) => (fn_did, args),
930 _ => return,
931 };
932 debug!(?fn_did, ?args);
933
934 let ty = tcx.type_of(fn_did).instantiate_identity();
936 debug!("ty: {:?}, ty.kind: {:?}", ty, ty.kind());
937 if let ty::Closure(_, _) = ty.kind() {
938 return;
939 }
940
941 if let Ok(Some(instance)) = ty::Instance::try_resolve(
942 tcx,
943 self.infcx.typing_env(self.infcx.param_env),
944 *fn_did,
945 self.infcx.resolve_vars_if_possible(args),
946 ) {
947 instance
948 } else {
949 return;
950 }
951 } else {
952 return;
953 };
954
955 let param = match find_param_with_region(tcx, self.mir_def_id(), f, o) {
956 Some(param) => param,
957 None => return,
958 };
959 debug!(?param);
960
961 let mut visitor = TraitObjectVisitor(FxIndexSet::default());
962 visitor.visit_ty(param.param_ty);
963
964 let Some((ident, self_ty)) = NiceRegionError::get_impl_ident_and_self_ty_from_trait(
965 tcx,
966 instance.def_id(),
967 &visitor.0,
968 ) else {
969 return;
970 };
971
972 self.suggest_constrain_dyn_trait_in_impl(diag, &visitor.0, ident, self_ty);
973 }
974
975 #[allow(rustc::diagnostic_outside_of_impl)]
976 #[instrument(skip(self, err), level = "debug")]
977 fn suggest_constrain_dyn_trait_in_impl(
978 &self,
979 err: &mut Diag<'_>,
980 found_dids: &FxIndexSet<DefId>,
981 ident: Ident,
982 self_ty: &hir::Ty<'_>,
983 ) -> bool {
984 debug!("err: {:#?}", err);
985 let mut suggested = false;
986 for found_did in found_dids {
987 let mut traits = vec![];
988 let mut hir_v = HirTraitObjectVisitor(&mut traits, *found_did);
989 hir_v.visit_ty_unambig(self_ty);
990 debug!("trait spans found: {:?}", traits);
991 for span in &traits {
992 let mut multi_span: MultiSpan = vec![*span].into();
993 multi_span.push_span_label(*span, fluent::borrowck_implicit_static);
994 multi_span.push_span_label(ident.span, fluent::borrowck_implicit_static_introduced);
995 err.subdiagnostic(RequireStaticErr::UsedImpl { multi_span });
996 err.span_suggestion_verbose(
997 span.shrink_to_hi(),
998 fluent::borrowck_implicit_static_relax,
999 " + '_",
1000 Applicability::MaybeIncorrect,
1001 );
1002 suggested = true;
1003 }
1004 }
1005 suggested
1006 }
1007
1008 fn suggest_adding_lifetime_params(&self, diag: &mut Diag<'_>, sub: RegionVid, sup: RegionVid) {
1009 let (Some(sub), Some(sup)) = (self.to_error_region(sub), self.to_error_region(sup)) else {
1010 return;
1011 };
1012
1013 let Some((ty_sub, _)) = self
1014 .infcx
1015 .tcx
1016 .is_suitable_region(self.mir_def_id(), sub)
1017 .and_then(|_| find_anon_type(self.infcx.tcx, self.mir_def_id(), sub))
1018 else {
1019 return;
1020 };
1021
1022 let Some((ty_sup, _)) = self
1023 .infcx
1024 .tcx
1025 .is_suitable_region(self.mir_def_id(), sup)
1026 .and_then(|_| find_anon_type(self.infcx.tcx, self.mir_def_id(), sup))
1027 else {
1028 return;
1029 };
1030
1031 suggest_adding_lifetime_params(
1032 self.infcx.tcx,
1033 diag,
1034 self.mir_def_id(),
1035 sub,
1036 ty_sup,
1037 ty_sub,
1038 );
1039 }
1040
1041 #[allow(rustc::diagnostic_outside_of_impl)]
1042 fn suggest_deref_closure_return(&self, diag: &mut Diag<'_>) {
1046 let tcx = self.infcx.tcx;
1047
1048 let closure_def_id = self.mir_def_id();
1050 let hir::Node::Expr(
1051 closure_expr @ hir::Expr {
1052 kind: hir::ExprKind::Closure(hir::Closure { body, .. }), ..
1053 },
1054 ) = tcx.hir_node_by_def_id(closure_def_id)
1055 else {
1056 return;
1057 };
1058 let ty::Closure(_, args) = *tcx.type_of(closure_def_id).instantiate_identity().kind()
1059 else {
1060 return;
1061 };
1062 let args = args.as_closure();
1063
1064 let parent_expr_id = tcx.parent_hir_id(self.mir_hir_id());
1066 let hir::Node::Expr(
1067 parent_expr @ hir::Expr {
1068 kind: hir::ExprKind::MethodCall(_, rcvr, call_args, _), ..
1069 },
1070 ) = tcx.hir_node(parent_expr_id)
1071 else {
1072 return;
1073 };
1074 let typeck_results = tcx.typeck(self.mir_def_id());
1075
1076 let liberated_sig = tcx.liberate_late_bound_regions(closure_def_id.to_def_id(), args.sig());
1078 let mut peeled_ty = liberated_sig.output();
1079 let mut count = 0;
1080 while let ty::Ref(_, ref_ty, _) = *peeled_ty.kind() {
1081 peeled_ty = ref_ty;
1082 count += 1;
1083 }
1084 if !self.infcx.type_is_copy_modulo_regions(self.infcx.param_env, peeled_ty) {
1085 return;
1086 }
1087
1088 let closure_sig_as_fn_ptr_ty = Ty::new_fn_ptr(
1090 tcx,
1091 ty::Binder::dummy(tcx.mk_fn_sig(
1092 liberated_sig.inputs().iter().copied(),
1093 peeled_ty,
1094 liberated_sig.c_variadic,
1095 hir::Safety::Safe,
1096 rustc_abi::ExternAbi::Rust,
1097 )),
1098 );
1099 let closure_ty = Ty::new_closure(
1100 tcx,
1101 closure_def_id.to_def_id(),
1102 ty::ClosureArgs::new(
1103 tcx,
1104 ty::ClosureArgsParts {
1105 parent_args: args.parent_args(),
1106 closure_kind_ty: args.kind_ty(),
1107 tupled_upvars_ty: args.tupled_upvars_ty(),
1108 closure_sig_as_fn_ptr_ty,
1109 },
1110 )
1111 .args,
1112 );
1113
1114 let Some((closure_arg_pos, _)) =
1115 call_args.iter().enumerate().find(|(_, arg)| arg.hir_id == closure_expr.hir_id)
1116 else {
1117 return;
1118 };
1119 let Some(method_def_id) = typeck_results.type_dependent_def_id(parent_expr.hir_id) else {
1122 return;
1123 };
1124 let Some(input_arg) = tcx
1125 .fn_sig(method_def_id)
1126 .skip_binder()
1127 .inputs()
1128 .skip_binder()
1129 .get(closure_arg_pos + 1)
1131 else {
1132 return;
1133 };
1134 let ty::Param(closure_param) = input_arg.kind() else { return };
1136
1137 let Some(possible_rcvr_ty) = typeck_results.node_type_opt(rcvr.hir_id) else { return };
1139 let args = GenericArgs::for_item(tcx, method_def_id, |param, _| {
1140 if let ty::GenericParamDefKind::Lifetime = param.kind {
1141 tcx.lifetimes.re_erased.into()
1142 } else if param.index == 0 && param.name == kw::SelfUpper {
1143 possible_rcvr_ty.into()
1144 } else if param.index == closure_param.index {
1145 closure_ty.into()
1146 } else {
1147 self.infcx.var_for_def(parent_expr.span, param)
1148 }
1149 });
1150
1151 let preds = tcx.predicates_of(method_def_id).instantiate(tcx, args);
1152
1153 let ocx = ObligationCtxt::new(&self.infcx);
1154 ocx.register_obligations(preds.iter().map(|(pred, span)| {
1155 trace!(?pred);
1156 Obligation::misc(tcx, span, self.mir_def_id(), self.infcx.param_env, pred)
1157 }));
1158
1159 if ocx.select_all_or_error().is_empty() && count > 0 {
1160 diag.span_suggestion_verbose(
1161 tcx.hir_body(*body).value.peel_blocks().span.shrink_to_lo(),
1162 fluent::borrowck_dereference_suggestion,
1163 "*".repeat(count),
1164 Applicability::MachineApplicable,
1165 );
1166 }
1167 }
1168
1169 #[allow(rustc::diagnostic_outside_of_impl)]
1170 fn suggest_move_on_borrowing_closure(&self, diag: &mut Diag<'_>) {
1171 let body = self.infcx.tcx.hir_body_owned_by(self.mir_def_id());
1172 let expr = &body.value.peel_blocks();
1173 let mut closure_span = None::<rustc_span::Span>;
1174 match expr.kind {
1175 hir::ExprKind::MethodCall(.., args, _) => {
1176 for arg in args {
1177 if let hir::ExprKind::Closure(hir::Closure {
1178 capture_clause: hir::CaptureBy::Ref,
1179 ..
1180 }) = arg.kind
1181 {
1182 closure_span = Some(arg.span.shrink_to_lo());
1183 break;
1184 }
1185 }
1186 }
1187 hir::ExprKind::Closure(hir::Closure {
1188 capture_clause: hir::CaptureBy::Ref,
1189 kind,
1190 ..
1191 }) => {
1192 if !matches!(
1193 kind,
1194 hir::ClosureKind::Coroutine(hir::CoroutineKind::Desugared(
1195 hir::CoroutineDesugaring::Async,
1196 _
1197 ),)
1198 ) {
1199 closure_span = Some(expr.span.shrink_to_lo());
1200 }
1201 }
1202 _ => {}
1203 }
1204 if let Some(closure_span) = closure_span {
1205 diag.span_suggestion_verbose(
1206 closure_span,
1207 fluent::borrowck_move_closure_suggestion,
1208 "move ",
1209 Applicability::MaybeIncorrect,
1210 );
1211 }
1212 }
1213}