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Commit | Line | Data |
---|---|---|
f9f354fc | 1 | use either::Either; |
dc9dc135 | 2 | use rustc_data_structures::fx::FxHashSet; |
dc9dc135 | 3 | use rustc_errors::{Applicability, DiagnosticBuilder}; |
dfeec247 XL |
4 | use rustc_hir as hir; |
5 | use rustc_hir::def_id::DefId; | |
6 | use rustc_hir::{AsyncGeneratorKind, GeneratorKind}; | |
7 | use rustc_index::vec::Idx; | |
ba9703b0 XL |
8 | use rustc_middle::mir::{ |
9 | self, AggregateKind, BindingForm, BorrowKind, ClearCrossCrate, ConstraintCategory, | |
10 | FakeReadCause, Local, LocalDecl, LocalInfo, LocalKind, Location, Operand, Place, PlaceRef, | |
11 | ProjectionElem, Rvalue, Statement, StatementKind, TerminatorKind, VarBindingForm, | |
12 | }; | |
f9f354fc | 13 | use rustc_middle::ty::{self, suggest_constraining_type_param, Ty}; |
dfeec247 XL |
14 | use rustc_span::source_map::DesugaringKind; |
15 | use rustc_span::Span; | |
dc9dc135 | 16 | |
dc9dc135 | 17 | use crate::dataflow::drop_flag_effects; |
dfeec247 | 18 | use crate::dataflow::indexes::{MoveOutIndex, MovePathIndex}; |
416331ca | 19 | use crate::util::borrowck_errors; |
dc9dc135 | 20 | |
60c5eb7d | 21 | use crate::borrow_check::{ |
dfeec247 XL |
22 | borrow_set::BorrowData, prefixes::IsPrefixOf, InitializationRequiringAction, MirBorrowckCtxt, |
23 | PrefixSet, WriteKind, | |
60c5eb7d XL |
24 | }; |
25 | ||
26 | use super::{ | |
f035d41b XL |
27 | explain_borrow::BorrowExplanation, FnSelfUseKind, IncludingDowncast, RegionName, |
28 | RegionNameSource, UseSpans, | |
60c5eb7d XL |
29 | }; |
30 | ||
dc9dc135 XL |
31 | #[derive(Debug)] |
32 | struct MoveSite { | |
33 | /// Index of the "move out" that we found. The `MoveData` can | |
34 | /// then tell us where the move occurred. | |
35 | moi: MoveOutIndex, | |
36 | ||
37 | /// `true` if we traversed a back edge while walking from the point | |
38 | /// of error to the move site. | |
dfeec247 | 39 | traversed_back_edge: bool, |
dc9dc135 XL |
40 | } |
41 | ||
42 | /// Which case a StorageDeadOrDrop is for. | |
43 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
44 | enum StorageDeadOrDrop<'tcx> { | |
45 | LocalStorageDead, | |
46 | BoxedStorageDead, | |
47 | Destructor(Ty<'tcx>), | |
48 | } | |
49 | ||
50 | impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { | |
60c5eb7d | 51 | pub(in crate::borrow_check) fn report_use_of_moved_or_uninitialized( |
dc9dc135 XL |
52 | &mut self, |
53 | location: Location, | |
54 | desired_action: InitializationRequiringAction, | |
74b04a01 | 55 | (moved_place, used_place, span): (PlaceRef<'tcx>, PlaceRef<'tcx>, Span), |
dc9dc135 XL |
56 | mpi: MovePathIndex, |
57 | ) { | |
58 | debug!( | |
59 | "report_use_of_moved_or_uninitialized: location={:?} desired_action={:?} \ | |
60 | moved_place={:?} used_place={:?} span={:?} mpi={:?}", | |
61 | location, desired_action, moved_place, used_place, span, mpi | |
62 | ); | |
63 | ||
dfeec247 XL |
64 | let use_spans = |
65 | self.move_spans(moved_place, location).or_else(|| self.borrow_spans(span, location)); | |
dc9dc135 XL |
66 | let span = use_spans.args_or_use(); |
67 | ||
68 | let move_site_vec = self.get_moved_indexes(location, mpi); | |
dfeec247 XL |
69 | debug!("report_use_of_moved_or_uninitialized: move_site_vec={:?}", move_site_vec); |
70 | let move_out_indices: Vec<_> = | |
71 | move_site_vec.iter().map(|move_site| move_site.moi).collect(); | |
dc9dc135 XL |
72 | |
73 | if move_out_indices.is_empty() { | |
60c5eb7d | 74 | let root_place = PlaceRef { projection: &[], ..used_place }; |
dc9dc135 | 75 | |
e74abb32 | 76 | if !self.uninitialized_error_reported.insert(root_place) { |
dc9dc135 XL |
77 | debug!( |
78 | "report_use_of_moved_or_uninitialized place: error about {:?} suppressed", | |
79 | root_place | |
80 | ); | |
81 | return; | |
82 | } | |
83 | ||
dfeec247 XL |
84 | let item_msg = |
85 | match self.describe_place_with_options(used_place, IncludingDowncast(true)) { | |
86 | Some(name) => format!("`{}`", name), | |
87 | None => "value".to_owned(), | |
88 | }; | |
416331ca | 89 | let mut err = self.cannot_act_on_uninitialized_variable( |
dc9dc135 XL |
90 | span, |
91 | desired_action.as_noun(), | |
dfeec247 XL |
92 | &self |
93 | .describe_place_with_options(moved_place, IncludingDowncast(true)) | |
dc9dc135 | 94 | .unwrap_or_else(|| "_".to_owned()), |
dc9dc135 | 95 | ); |
e1599b0c | 96 | err.span_label(span, format!("use of possibly-uninitialized {}", item_msg)); |
dc9dc135 XL |
97 | |
98 | use_spans.var_span_label( | |
99 | &mut err, | |
100 | format!("{} occurs due to use{}", desired_action.as_noun(), use_spans.describe()), | |
101 | ); | |
102 | ||
103 | err.buffer(&mut self.errors_buffer); | |
104 | } else { | |
105 | if let Some((reported_place, _)) = self.move_error_reported.get(&move_out_indices) { | |
dfeec247 | 106 | if self.prefixes(*reported_place, PrefixSet::All).any(|p| p == used_place) { |
dc9dc135 XL |
107 | debug!( |
108 | "report_use_of_moved_or_uninitialized place: error suppressed \ | |
109 | mois={:?}", | |
110 | move_out_indices | |
111 | ); | |
112 | return; | |
113 | } | |
114 | } | |
115 | ||
116 | let msg = ""; //FIXME: add "partially " or "collaterally " | |
117 | ||
416331ca | 118 | let mut err = self.cannot_act_on_moved_value( |
dc9dc135 XL |
119 | span, |
120 | desired_action.as_noun(), | |
121 | msg, | |
416331ca | 122 | self.describe_place_with_options(moved_place, IncludingDowncast(true)), |
dc9dc135 XL |
123 | ); |
124 | ||
dfeec247 | 125 | self.add_moved_or_invoked_closure_note(location, used_place, &mut err); |
dc9dc135 XL |
126 | |
127 | let mut is_loop_move = false; | |
128 | let is_partial_move = move_site_vec.iter().any(|move_site| { | |
129 | let move_out = self.move_data.moves[(*move_site).moi]; | |
130 | let moved_place = &self.move_data.move_paths[move_out.path].place; | |
dfeec247 | 131 | used_place != moved_place.as_ref() && used_place.is_prefix_of(moved_place.as_ref()) |
dc9dc135 XL |
132 | }); |
133 | for move_site in &move_site_vec { | |
134 | let move_out = self.move_data.moves[(*move_site).moi]; | |
135 | let moved_place = &self.move_data.move_paths[move_out.path].place; | |
136 | ||
416331ca | 137 | let move_spans = self.move_spans(moved_place.as_ref(), move_out.source); |
dc9dc135 XL |
138 | let move_span = move_spans.args_or_use(); |
139 | ||
dfeec247 | 140 | let move_msg = if move_spans.for_closure() { " into closure" } else { "" }; |
dc9dc135 | 141 | |
f035d41b | 142 | if location == move_out.source { |
dc9dc135 XL |
143 | err.span_label( |
144 | span, | |
145 | format!("value moved{} here, in previous iteration of loop", move_msg), | |
146 | ); | |
147 | is_loop_move = true; | |
148 | } else if move_site.traversed_back_edge { | |
149 | err.span_label( | |
150 | move_span, | |
dfeec247 | 151 | format!("value moved{} here, in previous iteration of loop", move_msg), |
dc9dc135 XL |
152 | ); |
153 | } else { | |
f035d41b XL |
154 | if let UseSpans::FnSelfUse { var_span, fn_call_span, fn_span, kind } = |
155 | move_spans | |
156 | { | |
157 | let place_name = self | |
158 | .describe_place(moved_place.as_ref()) | |
159 | .map(|n| format!("`{}`", n)) | |
160 | .unwrap_or_else(|| "value".to_owned()); | |
161 | match kind { | |
162 | FnSelfUseKind::FnOnceCall => { | |
163 | err.span_label( | |
164 | fn_call_span, | |
165 | &format!("{} moved due to this call", place_name), | |
166 | ); | |
167 | err.span_note( | |
168 | var_span, | |
169 | "this value implements `FnOnce`, which causes it to be moved when called", | |
170 | ); | |
171 | } | |
172 | FnSelfUseKind::Operator { self_arg } => { | |
173 | err.span_label( | |
174 | fn_call_span, | |
175 | &format!("{} moved due to usage in operator", place_name), | |
176 | ); | |
177 | if self.fn_self_span_reported.insert(fn_span) { | |
178 | err.span_note( | |
179 | self_arg.span, | |
180 | "calling this operator moves the left-hand side", | |
181 | ); | |
182 | } | |
183 | } | |
184 | FnSelfUseKind::Normal { self_arg, implicit_into_iter } => { | |
185 | if implicit_into_iter { | |
186 | err.span_label( | |
187 | fn_call_span, | |
188 | &format!( | |
189 | "{} moved due to this implicit call to `.into_iter()`", | |
190 | place_name | |
191 | ), | |
192 | ); | |
193 | } else { | |
194 | err.span_label( | |
195 | fn_call_span, | |
196 | &format!("{} moved due to this method call", place_name), | |
197 | ); | |
198 | } | |
199 | // Avoid pointing to the same function in multiple different | |
200 | // error messages | |
201 | if self.fn_self_span_reported.insert(self_arg.span) { | |
202 | err.span_note( | |
203 | self_arg.span, | |
204 | &format!("this function consumes the receiver `self` by taking ownership of it, which moves {}", place_name) | |
205 | ); | |
206 | } | |
207 | } | |
208 | } | |
209 | } else { | |
210 | err.span_label(move_span, format!("value moved{} here", move_msg)); | |
211 | move_spans.var_span_label( | |
212 | &mut err, | |
213 | format!("variable moved due to use{}", move_spans.describe()), | |
214 | ); | |
215 | } | |
216 | } | |
217 | if let UseSpans::PatUse(span) = move_spans { | |
218 | err.span_suggestion_verbose( | |
219 | span.shrink_to_lo(), | |
220 | &format!( | |
221 | "borrow this field in the pattern to avoid moving {}", | |
222 | self.describe_place(moved_place.as_ref()) | |
223 | .map(|n| format!("`{}`", n)) | |
224 | .unwrap_or_else(|| "the value".to_string()) | |
225 | ), | |
226 | "ref ".to_string(), | |
227 | Applicability::MachineApplicable, | |
dc9dc135 XL |
228 | ); |
229 | } | |
f035d41b XL |
230 | |
231 | if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() { | |
e1599b0c XL |
232 | let sess = self.infcx.tcx.sess; |
233 | if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) { | |
dc9dc135 XL |
234 | err.span_suggestion( |
235 | move_span, | |
236 | "consider borrowing to avoid moving into the for loop", | |
237 | format!("&{}", snippet), | |
238 | Applicability::MaybeIncorrect, | |
239 | ); | |
240 | } | |
241 | } | |
242 | } | |
243 | ||
244 | use_spans.var_span_label( | |
245 | &mut err, | |
246 | format!("{} occurs due to use{}", desired_action.as_noun(), use_spans.describe()), | |
247 | ); | |
248 | ||
249 | if !is_loop_move { | |
250 | err.span_label( | |
251 | span, | |
252 | format!( | |
253 | "value {} here {}", | |
254 | desired_action.as_verb_in_past_tense(), | |
255 | if is_partial_move { "after partial move" } else { "after move" }, | |
256 | ), | |
257 | ); | |
258 | } | |
259 | ||
dfeec247 | 260 | let ty = |
f9f354fc | 261 | Place::ty_from(used_place.local, used_place.projection, self.body, self.infcx.tcx) |
dfeec247 | 262 | .ty; |
e74abb32 | 263 | let needs_note = match ty.kind { |
dc9dc135 | 264 | ty::Closure(id, _) => { |
3dfed10e XL |
265 | let tables = self.infcx.tcx.typeck(id.expect_local()); |
266 | let hir_id = self.infcx.tcx.hir().local_def_id_to_hir_id(id.expect_local()); | |
dc9dc135 XL |
267 | |
268 | tables.closure_kind_origins().get(hir_id).is_none() | |
269 | } | |
270 | _ => true, | |
271 | }; | |
272 | ||
f035d41b XL |
273 | let mpi = self.move_data.moves[move_out_indices[0]].path; |
274 | let place = &self.move_data.move_paths[mpi].place; | |
275 | let ty = place.ty(self.body, self.infcx.tcx).ty; | |
276 | ||
277 | if is_loop_move { | |
278 | if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind { | |
279 | // We have a `&mut` ref, we need to reborrow on each iteration (#62112). | |
280 | err.span_suggestion_verbose( | |
281 | span.shrink_to_lo(), | |
282 | &format!( | |
283 | "consider creating a fresh reborrow of {} here", | |
284 | self.describe_place(moved_place) | |
285 | .map(|n| format!("`{}`", n)) | |
286 | .unwrap_or_else(|| "the mutable reference".to_string()), | |
287 | ), | |
288 | "&mut *".to_string(), | |
289 | Applicability::MachineApplicable, | |
290 | ); | |
291 | } | |
292 | } | |
dc9dc135 | 293 | |
f035d41b | 294 | if needs_note { |
416331ca XL |
295 | let opt_name = |
296 | self.describe_place_with_options(place.as_ref(), IncludingDowncast(true)); | |
dc9dc135 XL |
297 | let note_msg = match opt_name { |
298 | Some(ref name) => format!("`{}`", name), | |
299 | None => "value".to_owned(), | |
300 | }; | |
e74abb32 | 301 | if let ty::Param(param_ty) = ty.kind { |
dc9dc135 XL |
302 | let tcx = self.infcx.tcx; |
303 | let generics = tcx.generics_of(self.mir_def_id); | |
60c5eb7d XL |
304 | let param = generics.type_param(¶m_ty, tcx); |
305 | if let Some(generics) = | |
f9f354fc | 306 | tcx.hir().get_generics(tcx.closure_base_def_id(self.mir_def_id.to_def_id())) |
dfeec247 | 307 | { |
60c5eb7d | 308 | suggest_constraining_type_param( |
74b04a01 | 309 | tcx, |
60c5eb7d XL |
310 | generics, |
311 | &mut err, | |
312 | ¶m.name.as_str(), | |
313 | "Copy", | |
74b04a01 | 314 | None, |
dc9dc135 XL |
315 | ); |
316 | } | |
317 | } | |
e74abb32 XL |
318 | let span = if let Some(local) = place.as_local() { |
319 | let decl = &self.body.local_decls[local]; | |
dc9dc135 XL |
320 | Some(decl.source_info.span) |
321 | } else { | |
322 | None | |
323 | }; | |
dfeec247 | 324 | self.note_type_does_not_implement_copy(&mut err, ¬e_msg, ty, span); |
dc9dc135 XL |
325 | } |
326 | ||
dfeec247 XL |
327 | if let Some((_, mut old_err)) = |
328 | self.move_error_reported.insert(move_out_indices, (used_place, err)) | |
dc9dc135 XL |
329 | { |
330 | // Cancel the old error so it doesn't ICE. | |
331 | old_err.cancel(); | |
332 | } | |
333 | } | |
334 | } | |
335 | ||
60c5eb7d | 336 | pub(in crate::borrow_check) fn report_move_out_while_borrowed( |
dc9dc135 XL |
337 | &mut self, |
338 | location: Location, | |
ba9703b0 | 339 | (place, span): (Place<'tcx>, Span), |
dc9dc135 XL |
340 | borrow: &BorrowData<'tcx>, |
341 | ) { | |
342 | debug!( | |
343 | "report_move_out_while_borrowed: location={:?} place={:?} span={:?} borrow={:?}", | |
344 | location, place, span, borrow | |
345 | ); | |
ba9703b0 XL |
346 | let value_msg = self.describe_any_place(place.as_ref()); |
347 | let borrow_msg = self.describe_any_place(borrow.borrowed_place.as_ref()); | |
dc9dc135 XL |
348 | |
349 | let borrow_spans = self.retrieve_borrow_spans(borrow); | |
350 | let borrow_span = borrow_spans.args_or_use(); | |
351 | ||
416331ca | 352 | let move_spans = self.move_spans(place.as_ref(), location); |
dc9dc135 XL |
353 | let span = move_spans.args_or_use(); |
354 | ||
ba9703b0 XL |
355 | let mut err = |
356 | self.cannot_move_when_borrowed(span, &self.describe_any_place(place.as_ref())); | |
dc9dc135 XL |
357 | err.span_label(borrow_span, format!("borrow of {} occurs here", borrow_msg)); |
358 | err.span_label(span, format!("move out of {} occurs here", value_msg)); | |
359 | ||
360 | borrow_spans.var_span_label( | |
361 | &mut err, | |
dfeec247 | 362 | format!("borrow occurs due to use{}", borrow_spans.describe()), |
dc9dc135 XL |
363 | ); |
364 | ||
dfeec247 XL |
365 | move_spans |
366 | .var_span_label(&mut err, format!("move occurs due to use{}", move_spans.describe())); | |
dc9dc135 | 367 | |
dfeec247 XL |
368 | self.explain_why_borrow_contains_point(location, borrow, None) |
369 | .add_explanation_to_diagnostic( | |
370 | self.infcx.tcx, | |
371 | &self.body, | |
372 | &self.local_names, | |
373 | &mut err, | |
374 | "", | |
375 | Some(borrow_span), | |
376 | ); | |
dc9dc135 XL |
377 | err.buffer(&mut self.errors_buffer); |
378 | } | |
379 | ||
60c5eb7d | 380 | pub(in crate::borrow_check) fn report_use_while_mutably_borrowed( |
dc9dc135 XL |
381 | &mut self, |
382 | location: Location, | |
ba9703b0 | 383 | (place, _span): (Place<'tcx>, Span), |
dc9dc135 XL |
384 | borrow: &BorrowData<'tcx>, |
385 | ) -> DiagnosticBuilder<'cx> { | |
dc9dc135 XL |
386 | let borrow_spans = self.retrieve_borrow_spans(borrow); |
387 | let borrow_span = borrow_spans.args_or_use(); | |
388 | ||
389 | // Conflicting borrows are reported separately, so only check for move | |
390 | // captures. | |
416331ca | 391 | let use_spans = self.move_spans(place.as_ref(), location); |
dc9dc135 XL |
392 | let span = use_spans.var_or_use(); |
393 | ||
416331ca | 394 | let mut err = self.cannot_use_when_mutably_borrowed( |
dc9dc135 | 395 | span, |
ba9703b0 | 396 | &self.describe_any_place(place.as_ref()), |
dc9dc135 | 397 | borrow_span, |
ba9703b0 | 398 | &self.describe_any_place(borrow.borrowed_place.as_ref()), |
dc9dc135 XL |
399 | ); |
400 | ||
401 | borrow_spans.var_span_label(&mut err, { | |
402 | let place = &borrow.borrowed_place; | |
ba9703b0 XL |
403 | let desc_place = self.describe_any_place(place.as_ref()); |
404 | format!("borrow occurs due to use of {}{}", desc_place, borrow_spans.describe()) | |
dc9dc135 XL |
405 | }); |
406 | ||
407 | self.explain_why_borrow_contains_point(location, borrow, None) | |
60c5eb7d XL |
408 | .add_explanation_to_diagnostic( |
409 | self.infcx.tcx, | |
410 | &self.body, | |
411 | &self.local_names, | |
412 | &mut err, | |
413 | "", | |
414 | None, | |
415 | ); | |
dc9dc135 XL |
416 | err |
417 | } | |
418 | ||
60c5eb7d | 419 | pub(in crate::borrow_check) fn report_conflicting_borrow( |
dc9dc135 XL |
420 | &mut self, |
421 | location: Location, | |
ba9703b0 | 422 | (place, span): (Place<'tcx>, Span), |
dc9dc135 XL |
423 | gen_borrow_kind: BorrowKind, |
424 | issued_borrow: &BorrowData<'tcx>, | |
425 | ) -> DiagnosticBuilder<'cx> { | |
426 | let issued_spans = self.retrieve_borrow_spans(issued_borrow); | |
427 | let issued_span = issued_spans.args_or_use(); | |
428 | ||
429 | let borrow_spans = self.borrow_spans(span, location); | |
430 | let span = borrow_spans.args_or_use(); | |
431 | ||
432 | let container_name = if issued_spans.for_generator() || borrow_spans.for_generator() { | |
433 | "generator" | |
434 | } else { | |
435 | "closure" | |
436 | }; | |
437 | ||
438 | let (desc_place, msg_place, msg_borrow, union_type_name) = | |
ba9703b0 | 439 | self.describe_place_for_conflicting_borrow(place, issued_borrow.borrowed_place); |
dc9dc135 XL |
440 | |
441 | let explanation = self.explain_why_borrow_contains_point(location, issued_borrow, None); | |
dfeec247 | 442 | let second_borrow_desc = if explanation.is_explained() { "second " } else { "" }; |
dc9dc135 XL |
443 | |
444 | // FIXME: supply non-"" `opt_via` when appropriate | |
dc9dc135 | 445 | let first_borrow_desc; |
dfeec247 | 446 | let mut err = match (gen_borrow_kind, issued_borrow.kind) { |
60c5eb7d | 447 | (BorrowKind::Shared, BorrowKind::Mut { .. }) => { |
dc9dc135 | 448 | first_borrow_desc = "mutable "; |
416331ca | 449 | self.cannot_reborrow_already_borrowed( |
dc9dc135 XL |
450 | span, |
451 | &desc_place, | |
452 | &msg_place, | |
60c5eb7d | 453 | "immutable", |
dc9dc135 XL |
454 | issued_span, |
455 | "it", | |
60c5eb7d | 456 | "mutable", |
dc9dc135 XL |
457 | &msg_borrow, |
458 | None, | |
dc9dc135 XL |
459 | ) |
460 | } | |
60c5eb7d | 461 | (BorrowKind::Mut { .. }, BorrowKind::Shared) => { |
dc9dc135 | 462 | first_borrow_desc = "immutable "; |
416331ca | 463 | self.cannot_reborrow_already_borrowed( |
dc9dc135 XL |
464 | span, |
465 | &desc_place, | |
466 | &msg_place, | |
60c5eb7d | 467 | "mutable", |
dc9dc135 XL |
468 | issued_span, |
469 | "it", | |
60c5eb7d | 470 | "immutable", |
dc9dc135 XL |
471 | &msg_borrow, |
472 | None, | |
dc9dc135 XL |
473 | ) |
474 | } | |
475 | ||
60c5eb7d | 476 | (BorrowKind::Mut { .. }, BorrowKind::Mut { .. }) => { |
dc9dc135 | 477 | first_borrow_desc = "first "; |
74b04a01 | 478 | let mut err = self.cannot_mutably_borrow_multiply( |
dc9dc135 XL |
479 | span, |
480 | &desc_place, | |
481 | &msg_place, | |
482 | issued_span, | |
483 | &msg_borrow, | |
484 | None, | |
74b04a01 XL |
485 | ); |
486 | self.suggest_split_at_mut_if_applicable( | |
487 | &mut err, | |
ba9703b0 XL |
488 | place, |
489 | issued_borrow.borrowed_place, | |
74b04a01 XL |
490 | ); |
491 | err | |
dc9dc135 XL |
492 | } |
493 | ||
60c5eb7d | 494 | (BorrowKind::Unique, BorrowKind::Unique) => { |
dc9dc135 | 495 | first_borrow_desc = "first "; |
dfeec247 | 496 | self.cannot_uniquely_borrow_by_two_closures(span, &desc_place, issued_span, None) |
dc9dc135 XL |
497 | } |
498 | ||
ba9703b0 | 499 | (BorrowKind::Mut { .. } | BorrowKind::Unique, BorrowKind::Shallow) => { |
dfeec247 | 500 | if let Some(immutable_section_description) = |
ba9703b0 | 501 | self.classify_immutable_section(issued_borrow.assigned_place) |
dfeec247 | 502 | { |
60c5eb7d XL |
503 | let mut err = self.cannot_mutate_in_immutable_section( |
504 | span, | |
505 | issued_span, | |
506 | &desc_place, | |
507 | immutable_section_description, | |
508 | "mutably borrow", | |
509 | ); | |
510 | borrow_spans.var_span_label( | |
511 | &mut err, | |
512 | format!( | |
ba9703b0 | 513 | "borrow occurs due to use of {}{}", |
60c5eb7d XL |
514 | desc_place, |
515 | borrow_spans.describe(), | |
516 | ), | |
517 | ); | |
dc9dc135 | 518 | |
60c5eb7d XL |
519 | return err; |
520 | } else { | |
521 | first_borrow_desc = "immutable "; | |
522 | self.cannot_reborrow_already_borrowed( | |
523 | span, | |
524 | &desc_place, | |
525 | &msg_place, | |
526 | "mutable", | |
527 | issued_span, | |
528 | "it", | |
529 | "immutable", | |
530 | &msg_borrow, | |
531 | None, | |
532 | ) | |
533 | } | |
dc9dc135 XL |
534 | } |
535 | ||
60c5eb7d | 536 | (BorrowKind::Unique, _) => { |
dc9dc135 | 537 | first_borrow_desc = "first "; |
416331ca | 538 | self.cannot_uniquely_borrow_by_one_closure( |
dc9dc135 XL |
539 | span, |
540 | container_name, | |
541 | &desc_place, | |
542 | "", | |
543 | issued_span, | |
544 | "it", | |
545 | "", | |
546 | None, | |
dc9dc135 | 547 | ) |
dfeec247 | 548 | } |
dc9dc135 | 549 | |
60c5eb7d | 550 | (BorrowKind::Shared, BorrowKind::Unique) => { |
dc9dc135 | 551 | first_borrow_desc = "first "; |
416331ca | 552 | self.cannot_reborrow_already_uniquely_borrowed( |
dc9dc135 XL |
553 | span, |
554 | container_name, | |
555 | &desc_place, | |
556 | "", | |
60c5eb7d | 557 | "immutable", |
dc9dc135 XL |
558 | issued_span, |
559 | "", | |
560 | None, | |
561 | second_borrow_desc, | |
dc9dc135 XL |
562 | ) |
563 | } | |
564 | ||
60c5eb7d | 565 | (BorrowKind::Mut { .. }, BorrowKind::Unique) => { |
dc9dc135 | 566 | first_borrow_desc = "first "; |
416331ca | 567 | self.cannot_reborrow_already_uniquely_borrowed( |
dc9dc135 XL |
568 | span, |
569 | container_name, | |
570 | &desc_place, | |
571 | "", | |
60c5eb7d | 572 | "mutable", |
dc9dc135 XL |
573 | issued_span, |
574 | "", | |
575 | None, | |
576 | second_borrow_desc, | |
dc9dc135 XL |
577 | ) |
578 | } | |
579 | ||
ba9703b0 XL |
580 | (BorrowKind::Shared, BorrowKind::Shared | BorrowKind::Shallow) |
581 | | ( | |
582 | BorrowKind::Shallow, | |
583 | BorrowKind::Mut { .. } | |
584 | | BorrowKind::Unique | |
585 | | BorrowKind::Shared | |
586 | | BorrowKind::Shallow, | |
587 | ) => unreachable!(), | |
dc9dc135 XL |
588 | }; |
589 | ||
590 | if issued_spans == borrow_spans { | |
591 | borrow_spans.var_span_label( | |
592 | &mut err, | |
ba9703b0 | 593 | format!("borrows occur due to use of {}{}", desc_place, borrow_spans.describe()), |
dc9dc135 XL |
594 | ); |
595 | } else { | |
596 | let borrow_place = &issued_borrow.borrowed_place; | |
ba9703b0 | 597 | let borrow_place_desc = self.describe_any_place(borrow_place.as_ref()); |
dc9dc135 XL |
598 | issued_spans.var_span_label( |
599 | &mut err, | |
600 | format!( | |
ba9703b0 | 601 | "first borrow occurs due to use of {}{}", |
dc9dc135 XL |
602 | borrow_place_desc, |
603 | issued_spans.describe(), | |
604 | ), | |
605 | ); | |
606 | ||
607 | borrow_spans.var_span_label( | |
608 | &mut err, | |
609 | format!( | |
ba9703b0 | 610 | "second borrow occurs due to use of {}{}", |
dc9dc135 XL |
611 | desc_place, |
612 | borrow_spans.describe(), | |
613 | ), | |
614 | ); | |
615 | } | |
616 | ||
617 | if union_type_name != "" { | |
618 | err.note(&format!( | |
ba9703b0 | 619 | "{} is a field of the union `{}`, so it overlaps the field {}", |
dc9dc135 XL |
620 | msg_place, union_type_name, msg_borrow, |
621 | )); | |
622 | } | |
623 | ||
624 | explanation.add_explanation_to_diagnostic( | |
625 | self.infcx.tcx, | |
60c5eb7d XL |
626 | &self.body, |
627 | &self.local_names, | |
dc9dc135 XL |
628 | &mut err, |
629 | first_borrow_desc, | |
630 | None, | |
631 | ); | |
632 | ||
633 | err | |
634 | } | |
635 | ||
74b04a01 XL |
636 | fn suggest_split_at_mut_if_applicable( |
637 | &self, | |
638 | err: &mut DiagnosticBuilder<'_>, | |
ba9703b0 XL |
639 | place: Place<'tcx>, |
640 | borrowed_place: Place<'tcx>, | |
74b04a01 | 641 | ) { |
ba9703b0 XL |
642 | if let ([ProjectionElem::Index(_)], [ProjectionElem::Index(_)]) = |
643 | (&place.projection[..], &borrowed_place.projection[..]) | |
644 | { | |
645 | err.help( | |
646 | "consider using `.split_at_mut(position)` or similar method to obtain \ | |
74b04a01 | 647 | two mutable non-overlapping sub-slices", |
ba9703b0 | 648 | ); |
74b04a01 XL |
649 | } |
650 | } | |
651 | ||
dc9dc135 XL |
652 | /// Returns the description of the root place for a conflicting borrow and the full |
653 | /// descriptions of the places that caused the conflict. | |
654 | /// | |
655 | /// In the simplest case, where there are no unions involved, if a mutable borrow of `x` is | |
656 | /// attempted while a shared borrow is live, then this function will return: | |
657 | /// | |
658 | /// ("x", "", "") | |
659 | /// | |
660 | /// In the simple union case, if a mutable borrow of a union field `x.z` is attempted while | |
661 | /// a shared borrow of another field `x.y`, then this function will return: | |
662 | /// | |
663 | /// ("x", "x.z", "x.y") | |
664 | /// | |
665 | /// In the more complex union case, where the union is a field of a struct, then if a mutable | |
666 | /// borrow of a union field in a struct `x.u.z` is attempted while a shared borrow of | |
667 | /// another field `x.u.y`, then this function will return: | |
668 | /// | |
669 | /// ("x.u", "x.u.z", "x.u.y") | |
670 | /// | |
671 | /// This is used when creating error messages like below: | |
672 | /// | |
f9f354fc XL |
673 | /// ```text |
674 | /// cannot borrow `a.u` (via `a.u.z.c`) as immutable because it is also borrowed as | |
675 | /// mutable (via `a.u.s.b`) [E0502] | |
676 | /// ``` | |
60c5eb7d | 677 | pub(in crate::borrow_check) fn describe_place_for_conflicting_borrow( |
dc9dc135 | 678 | &self, |
ba9703b0 XL |
679 | first_borrowed_place: Place<'tcx>, |
680 | second_borrowed_place: Place<'tcx>, | |
dc9dc135 XL |
681 | ) -> (String, String, String, String) { |
682 | // Define a small closure that we can use to check if the type of a place | |
683 | // is a union. | |
416331ca | 684 | let union_ty = |place_base, place_projection| { |
f9f354fc | 685 | let ty = Place::ty_from(place_base, place_projection, self.body, self.infcx.tcx).ty; |
dc9dc135 XL |
686 | ty.ty_adt_def().filter(|adt| adt.is_union()).map(|_| ty) |
687 | }; | |
dc9dc135 XL |
688 | |
689 | // Start with an empty tuple, so we can use the functions on `Option` to reduce some | |
690 | // code duplication (particularly around returning an empty description in the failure | |
691 | // case). | |
692 | Some(()) | |
693 | .filter(|_| { | |
694 | // If we have a conflicting borrow of the same place, then we don't want to add | |
695 | // an extraneous "via x.y" to our diagnostics, so filter out this case. | |
696 | first_borrowed_place != second_borrowed_place | |
697 | }) | |
698 | .and_then(|_| { | |
699 | // We're going to want to traverse the first borrowed place to see if we can find | |
700 | // field access to a union. If we find that, then we will keep the place of the | |
701 | // union being accessed and the field that was being accessed so we can check the | |
702 | // second borrowed place for the same union and a access to a different field. | |
dfeec247 | 703 | let Place { local, projection } = first_borrowed_place; |
416331ca | 704 | |
e74abb32 | 705 | let mut cursor = projection.as_ref(); |
e1599b0c XL |
706 | while let [proj_base @ .., elem] = cursor { |
707 | cursor = proj_base; | |
416331ca | 708 | |
dc9dc135 | 709 | match elem { |
ba9703b0 XL |
710 | ProjectionElem::Field(field, _) if union_ty(local, proj_base).is_some() => { |
711 | return Some((PlaceRef { local, projection: proj_base }, field)); | |
dfeec247 XL |
712 | } |
713 | _ => {} | |
dc9dc135 XL |
714 | } |
715 | } | |
716 | None | |
717 | }) | |
718 | .and_then(|(target_base, target_field)| { | |
719 | // With the place of a union and a field access into it, we traverse the second | |
720 | // borrowed place and look for a access to a different field of the same union. | |
ba9703b0 | 721 | let Place { local, ref projection } = second_borrowed_place; |
416331ca | 722 | |
74b04a01 | 723 | let mut cursor = &projection[..]; |
e1599b0c XL |
724 | while let [proj_base @ .., elem] = cursor { |
725 | cursor = proj_base; | |
416331ca | 726 | |
dc9dc135 | 727 | if let ProjectionElem::Field(field, _) = elem { |
ba9703b0 | 728 | if let Some(union_ty) = union_ty(local, proj_base) { |
416331ca | 729 | if field != target_field |
ba9703b0 | 730 | && local == target_base.local |
dfeec247 XL |
731 | && proj_base == target_base.projection |
732 | { | |
dc9dc135 | 733 | return Some(( |
ba9703b0 XL |
734 | self.describe_any_place(PlaceRef { |
735 | local, | |
736 | projection: proj_base, | |
737 | }), | |
738 | self.describe_any_place(first_borrowed_place.as_ref()), | |
739 | self.describe_any_place(second_borrowed_place.as_ref()), | |
dc9dc135 XL |
740 | union_ty.to_string(), |
741 | )); | |
742 | } | |
743 | } | |
744 | } | |
dc9dc135 XL |
745 | } |
746 | None | |
747 | }) | |
748 | .unwrap_or_else(|| { | |
749 | // If we didn't find a field access into a union, or both places match, then | |
750 | // only return the description of the first place. | |
751 | ( | |
ba9703b0 | 752 | self.describe_any_place(first_borrowed_place.as_ref()), |
dc9dc135 XL |
753 | "".to_string(), |
754 | "".to_string(), | |
755 | "".to_string(), | |
756 | ) | |
757 | }) | |
758 | } | |
759 | ||
760 | /// Reports StorageDeadOrDrop of `place` conflicts with `borrow`. | |
761 | /// | |
762 | /// This means that some data referenced by `borrow` needs to live | |
763 | /// past the point where the StorageDeadOrDrop of `place` occurs. | |
764 | /// This is usually interpreted as meaning that `place` has too | |
765 | /// short a lifetime. (But sometimes it is more useful to report | |
766 | /// it as a more direct conflict between the execution of a | |
767 | /// `Drop::drop` with an aliasing borrow.) | |
60c5eb7d | 768 | pub(in crate::borrow_check) fn report_borrowed_value_does_not_live_long_enough( |
dc9dc135 XL |
769 | &mut self, |
770 | location: Location, | |
771 | borrow: &BorrowData<'tcx>, | |
ba9703b0 | 772 | place_span: (Place<'tcx>, Span), |
dc9dc135 XL |
773 | kind: Option<WriteKind>, |
774 | ) { | |
775 | debug!( | |
776 | "report_borrowed_value_does_not_live_long_enough(\ | |
777 | {:?}, {:?}, {:?}, {:?}\ | |
778 | )", | |
779 | location, borrow, place_span, kind | |
780 | ); | |
781 | ||
782 | let drop_span = place_span.1; | |
dfeec247 XL |
783 | let root_place = |
784 | self.prefixes(borrow.borrowed_place.as_ref(), PrefixSet::All).last().unwrap(); | |
dc9dc135 XL |
785 | |
786 | let borrow_spans = self.retrieve_borrow_spans(borrow); | |
787 | let borrow_span = borrow_spans.var_or_use(); | |
788 | ||
e1599b0c | 789 | assert!(root_place.projection.is_empty()); |
74b04a01 | 790 | let proper_span = self.body.local_decls[root_place.local].source_info.span; |
dc9dc135 | 791 | |
e74abb32 XL |
792 | let root_place_projection = self.infcx.tcx.intern_place_elems(root_place.projection); |
793 | ||
dfeec247 | 794 | if self.access_place_error_reported.contains(&( |
74b04a01 | 795 | Place { local: root_place.local, projection: root_place_projection }, |
dfeec247 XL |
796 | borrow_span, |
797 | )) { | |
dc9dc135 XL |
798 | debug!( |
799 | "suppressing access_place error when borrow doesn't live long enough for {:?}", | |
800 | borrow_span | |
801 | ); | |
802 | return; | |
803 | } | |
804 | ||
dfeec247 | 805 | self.access_place_error_reported.insert(( |
74b04a01 | 806 | Place { local: root_place.local, projection: root_place_projection }, |
dfeec247 XL |
807 | borrow_span, |
808 | )); | |
dc9dc135 | 809 | |
dfeec247 XL |
810 | let borrowed_local = borrow.borrowed_place.local; |
811 | if self.body.local_decls[borrowed_local].is_ref_to_thread_local() { | |
812 | let err = | |
813 | self.report_thread_local_value_does_not_live_long_enough(drop_span, borrow_span); | |
814 | err.buffer(&mut self.errors_buffer); | |
815 | return; | |
816 | } | |
60c5eb7d | 817 | |
dc9dc135 | 818 | if let StorageDeadOrDrop::Destructor(dropped_ty) = |
416331ca | 819 | self.classify_drop_access_kind(borrow.borrowed_place.as_ref()) |
dc9dc135 XL |
820 | { |
821 | // If a borrow of path `B` conflicts with drop of `D` (and | |
822 | // we're not in the uninteresting case where `B` is a | |
823 | // prefix of `D`), then report this as a more interesting | |
824 | // destructor conflict. | |
416331ca | 825 | if !borrow.borrowed_place.as_ref().is_prefix_of(place_span.0.as_ref()) { |
dc9dc135 XL |
826 | self.report_borrow_conflicts_with_destructor( |
827 | location, borrow, place_span, kind, dropped_ty, | |
828 | ); | |
829 | return; | |
830 | } | |
831 | } | |
832 | ||
416331ca | 833 | let place_desc = self.describe_place(borrow.borrowed_place.as_ref()); |
dc9dc135 XL |
834 | |
835 | let kind_place = kind.filter(|_| place_desc.is_some()).map(|k| (k, place_span.0)); | |
836 | let explanation = self.explain_why_borrow_contains_point(location, &borrow, kind_place); | |
837 | ||
e74abb32 XL |
838 | debug!( |
839 | "report_borrowed_value_does_not_live_long_enough(place_desc: {:?}, explanation: {:?})", | |
dfeec247 | 840 | place_desc, explanation |
e74abb32 | 841 | ); |
dc9dc135 | 842 | let err = match (place_desc, explanation) { |
dc9dc135 XL |
843 | // If the outlives constraint comes from inside the closure, |
844 | // for example: | |
845 | // | |
846 | // let x = 0; | |
847 | // let y = &x; | |
848 | // Box::new(|| y) as Box<Fn() -> &'static i32> | |
849 | // | |
850 | // then just use the normal error. The closure isn't escaping | |
851 | // and `move` will not help here. | |
852 | ( | |
853 | Some(ref name), | |
854 | BorrowExplanation::MustBeValidFor { | |
ba9703b0 XL |
855 | category: |
856 | category | |
857 | @ | |
f035d41b | 858 | (ConstraintCategory::Return(_) |
ba9703b0 XL |
859 | | ConstraintCategory::CallArgument |
860 | | ConstraintCategory::OpaqueType), | |
dc9dc135 XL |
861 | from_closure: false, |
862 | ref region_name, | |
863 | span, | |
864 | .. | |
865 | }, | |
ba9703b0 XL |
866 | ) if borrow_spans.for_generator() | borrow_spans.for_closure() => self |
867 | .report_escaping_closure_capture( | |
868 | borrow_spans, | |
869 | borrow_span, | |
870 | region_name, | |
871 | category, | |
e74abb32 | 872 | span, |
ba9703b0 XL |
873 | &format!("`{}`", name), |
874 | ), | |
dc9dc135 XL |
875 | ( |
876 | ref name, | |
877 | BorrowExplanation::MustBeValidFor { | |
878 | category: ConstraintCategory::Assignment, | |
879 | from_closure: false, | |
dfeec247 XL |
880 | region_name: |
881 | RegionName { | |
882 | source: | |
883 | RegionNameSource::AnonRegionFromUpvar(upvar_span, ref upvar_name), | |
884 | .. | |
885 | }, | |
dc9dc135 XL |
886 | span, |
887 | .. | |
888 | }, | |
889 | ) => self.report_escaping_data(borrow_span, name, upvar_span, upvar_name, span), | |
890 | (Some(name), explanation) => self.report_local_value_does_not_live_long_enough( | |
891 | location, | |
892 | &name, | |
893 | &borrow, | |
894 | drop_span, | |
895 | borrow_spans, | |
896 | explanation, | |
897 | ), | |
898 | (None, explanation) => self.report_temporary_value_does_not_live_long_enough( | |
899 | location, | |
900 | &borrow, | |
901 | drop_span, | |
902 | borrow_spans, | |
903 | proper_span, | |
904 | explanation, | |
905 | ), | |
906 | }; | |
907 | ||
908 | err.buffer(&mut self.errors_buffer); | |
909 | } | |
910 | ||
911 | fn report_local_value_does_not_live_long_enough( | |
912 | &mut self, | |
913 | location: Location, | |
914 | name: &str, | |
915 | borrow: &BorrowData<'tcx>, | |
916 | drop_span: Span, | |
917 | borrow_spans: UseSpans, | |
918 | explanation: BorrowExplanation, | |
919 | ) -> DiagnosticBuilder<'cx> { | |
920 | debug!( | |
921 | "report_local_value_does_not_live_long_enough(\ | |
922 | {:?}, {:?}, {:?}, {:?}, {:?}\ | |
923 | )", | |
924 | location, name, borrow, drop_span, borrow_spans | |
925 | ); | |
926 | ||
927 | let borrow_span = borrow_spans.var_or_use(); | |
928 | if let BorrowExplanation::MustBeValidFor { | |
929 | category, | |
930 | span, | |
931 | ref opt_place_desc, | |
932 | from_closure: false, | |
933 | .. | |
dfeec247 XL |
934 | } = explanation |
935 | { | |
dc9dc135 XL |
936 | if let Some(diag) = self.try_report_cannot_return_reference_to_local( |
937 | borrow, | |
938 | borrow_span, | |
939 | span, | |
940 | category, | |
941 | opt_place_desc.as_ref(), | |
942 | ) { | |
943 | return diag; | |
944 | } | |
945 | } | |
946 | ||
dfeec247 | 947 | let mut err = self.path_does_not_live_long_enough(borrow_span, &format!("`{}`", name)); |
dc9dc135 XL |
948 | |
949 | if let Some(annotation) = self.annotate_argument_and_return_for_borrow(borrow) { | |
950 | let region_name = annotation.emit(self, &mut err); | |
951 | ||
952 | err.span_label( | |
953 | borrow_span, | |
954 | format!("`{}` would have to be valid for `{}`...", name, region_name), | |
955 | ); | |
956 | ||
3dfed10e | 957 | let fn_hir_id = self.infcx.tcx.hir().local_def_id_to_hir_id(self.mir_def_id); |
f9f354fc XL |
958 | err.span_label( |
959 | drop_span, | |
960 | format!( | |
961 | "...but `{}` will be dropped here, when the {} returns", | |
962 | name, | |
963 | self.infcx | |
964 | .tcx | |
965 | .hir() | |
966 | .opt_name(fn_hir_id) | |
967 | .map(|name| format!("function `{}`", name)) | |
968 | .unwrap_or_else(|| { | |
3dfed10e | 969 | match &self.infcx.tcx.typeck(self.mir_def_id).node_type(fn_hir_id).kind |
f9f354fc XL |
970 | { |
971 | ty::Closure(..) => "enclosing closure", | |
972 | ty::Generator(..) => "enclosing generator", | |
973 | kind => bug!("expected closure or generator, found {:?}", kind), | |
974 | } | |
975 | .to_string() | |
976 | }) | |
977 | ), | |
978 | ); | |
dc9dc135 | 979 | |
f9f354fc XL |
980 | err.note( |
981 | "functions cannot return a borrow to data owned within the function's scope, \ | |
982 | functions can only return borrows to data passed as arguments", | |
983 | ); | |
984 | err.note( | |
985 | "to learn more, visit <https://doc.rust-lang.org/book/ch04-02-\ | |
986 | references-and-borrowing.html#dangling-references>", | |
987 | ); | |
dc9dc135 XL |
988 | |
989 | if let BorrowExplanation::MustBeValidFor { .. } = explanation { | |
990 | } else { | |
991 | explanation.add_explanation_to_diagnostic( | |
992 | self.infcx.tcx, | |
60c5eb7d XL |
993 | &self.body, |
994 | &self.local_names, | |
dc9dc135 XL |
995 | &mut err, |
996 | "", | |
997 | None, | |
998 | ); | |
999 | } | |
1000 | } else { | |
1001 | err.span_label(borrow_span, "borrowed value does not live long enough"); | |
dfeec247 | 1002 | err.span_label(drop_span, format!("`{}` dropped here while still borrowed", name)); |
dc9dc135 | 1003 | |
dfeec247 | 1004 | let within = if borrow_spans.for_generator() { " by generator" } else { "" }; |
dc9dc135 | 1005 | |
dfeec247 | 1006 | borrow_spans.args_span_label(&mut err, format!("value captured here{}", within)); |
dc9dc135 XL |
1007 | |
1008 | explanation.add_explanation_to_diagnostic( | |
dfeec247 XL |
1009 | self.infcx.tcx, |
1010 | &self.body, | |
1011 | &self.local_names, | |
1012 | &mut err, | |
1013 | "", | |
1014 | None, | |
1015 | ); | |
dc9dc135 XL |
1016 | } |
1017 | ||
1018 | err | |
1019 | } | |
1020 | ||
1021 | fn report_borrow_conflicts_with_destructor( | |
1022 | &mut self, | |
1023 | location: Location, | |
1024 | borrow: &BorrowData<'tcx>, | |
ba9703b0 | 1025 | (place, drop_span): (Place<'tcx>, Span), |
dc9dc135 XL |
1026 | kind: Option<WriteKind>, |
1027 | dropped_ty: Ty<'tcx>, | |
1028 | ) { | |
1029 | debug!( | |
1030 | "report_borrow_conflicts_with_destructor(\ | |
1031 | {:?}, {:?}, ({:?}, {:?}), {:?}\ | |
1032 | )", | |
1033 | location, borrow, place, drop_span, kind, | |
1034 | ); | |
1035 | ||
1036 | let borrow_spans = self.retrieve_borrow_spans(borrow); | |
1037 | let borrow_span = borrow_spans.var_or_use(); | |
1038 | ||
416331ca | 1039 | let mut err = self.cannot_borrow_across_destructor(borrow_span); |
dc9dc135 | 1040 | |
416331ca | 1041 | let what_was_dropped = match self.describe_place(place.as_ref()) { |
60c5eb7d | 1042 | Some(name) => format!("`{}`", name), |
dc9dc135 XL |
1043 | None => String::from("temporary value"), |
1044 | }; | |
1045 | ||
416331ca | 1046 | let label = match self.describe_place(borrow.borrowed_place.as_ref()) { |
dc9dc135 XL |
1047 | Some(borrowed) => format!( |
1048 | "here, drop of {D} needs exclusive access to `{B}`, \ | |
1049 | because the type `{T}` implements the `Drop` trait", | |
1050 | D = what_was_dropped, | |
1051 | T = dropped_ty, | |
1052 | B = borrowed | |
1053 | ), | |
1054 | None => format!( | |
1055 | "here is drop of {D}; whose type `{T}` implements the `Drop` trait", | |
1056 | D = what_was_dropped, | |
1057 | T = dropped_ty | |
1058 | ), | |
1059 | }; | |
1060 | err.span_label(drop_span, label); | |
1061 | ||
1062 | // Only give this note and suggestion if they could be relevant. | |
1063 | let explanation = | |
1064 | self.explain_why_borrow_contains_point(location, borrow, kind.map(|k| (k, place))); | |
1065 | match explanation { | |
1066 | BorrowExplanation::UsedLater { .. } | |
1067 | | BorrowExplanation::UsedLaterWhenDropped { .. } => { | |
1068 | err.note("consider using a `let` binding to create a longer lived value"); | |
1069 | } | |
1070 | _ => {} | |
1071 | } | |
1072 | ||
60c5eb7d XL |
1073 | explanation.add_explanation_to_diagnostic( |
1074 | self.infcx.tcx, | |
1075 | &self.body, | |
1076 | &self.local_names, | |
1077 | &mut err, | |
1078 | "", | |
1079 | None, | |
1080 | ); | |
dc9dc135 XL |
1081 | |
1082 | err.buffer(&mut self.errors_buffer); | |
1083 | } | |
1084 | ||
1085 | fn report_thread_local_value_does_not_live_long_enough( | |
1086 | &mut self, | |
1087 | drop_span: Span, | |
1088 | borrow_span: Span, | |
1089 | ) -> DiagnosticBuilder<'cx> { | |
1090 | debug!( | |
1091 | "report_thread_local_value_does_not_live_long_enough(\ | |
1092 | {:?}, {:?}\ | |
1093 | )", | |
1094 | drop_span, borrow_span | |
1095 | ); | |
1096 | ||
416331ca | 1097 | let mut err = self.thread_local_value_does_not_live_long_enough(borrow_span); |
dc9dc135 XL |
1098 | |
1099 | err.span_label( | |
1100 | borrow_span, | |
1101 | "thread-local variables cannot be borrowed beyond the end of the function", | |
1102 | ); | |
1103 | err.span_label(drop_span, "end of enclosing function is here"); | |
1104 | ||
1105 | err | |
1106 | } | |
1107 | ||
1108 | fn report_temporary_value_does_not_live_long_enough( | |
1109 | &mut self, | |
1110 | location: Location, | |
1111 | borrow: &BorrowData<'tcx>, | |
1112 | drop_span: Span, | |
1113 | borrow_spans: UseSpans, | |
1114 | proper_span: Span, | |
1115 | explanation: BorrowExplanation, | |
1116 | ) -> DiagnosticBuilder<'cx> { | |
1117 | debug!( | |
1118 | "report_temporary_value_does_not_live_long_enough(\ | |
1119 | {:?}, {:?}, {:?}, {:?}\ | |
1120 | )", | |
1121 | location, borrow, drop_span, proper_span | |
1122 | ); | |
1123 | ||
dfeec247 XL |
1124 | if let BorrowExplanation::MustBeValidFor { category, span, from_closure: false, .. } = |
1125 | explanation | |
1126 | { | |
dc9dc135 XL |
1127 | if let Some(diag) = self.try_report_cannot_return_reference_to_local( |
1128 | borrow, | |
1129 | proper_span, | |
1130 | span, | |
1131 | category, | |
1132 | None, | |
1133 | ) { | |
1134 | return diag; | |
1135 | } | |
1136 | } | |
1137 | ||
416331ca | 1138 | let mut err = self.temporary_value_borrowed_for_too_long(proper_span); |
dfeec247 XL |
1139 | err.span_label(proper_span, "creates a temporary which is freed while still in use"); |
1140 | err.span_label(drop_span, "temporary value is freed at the end of this statement"); | |
dc9dc135 XL |
1141 | |
1142 | match explanation { | |
1143 | BorrowExplanation::UsedLater(..) | |
1144 | | BorrowExplanation::UsedLaterInLoop(..) | |
1145 | | BorrowExplanation::UsedLaterWhenDropped { .. } => { | |
1146 | // Only give this note and suggestion if it could be relevant. | |
1147 | err.note("consider using a `let` binding to create a longer lived value"); | |
1148 | } | |
1149 | _ => {} | |
1150 | } | |
60c5eb7d XL |
1151 | explanation.add_explanation_to_diagnostic( |
1152 | self.infcx.tcx, | |
1153 | &self.body, | |
1154 | &self.local_names, | |
1155 | &mut err, | |
1156 | "", | |
1157 | None, | |
1158 | ); | |
dc9dc135 | 1159 | |
dfeec247 | 1160 | let within = if borrow_spans.for_generator() { " by generator" } else { "" }; |
dc9dc135 | 1161 | |
dfeec247 | 1162 | borrow_spans.args_span_label(&mut err, format!("value captured here{}", within)); |
dc9dc135 XL |
1163 | |
1164 | err | |
1165 | } | |
1166 | ||
1167 | fn try_report_cannot_return_reference_to_local( | |
1168 | &self, | |
1169 | borrow: &BorrowData<'tcx>, | |
1170 | borrow_span: Span, | |
1171 | return_span: Span, | |
1172 | category: ConstraintCategory, | |
1173 | opt_place_desc: Option<&String>, | |
1174 | ) -> Option<DiagnosticBuilder<'cx>> { | |
dc9dc135 | 1175 | let return_kind = match category { |
f035d41b | 1176 | ConstraintCategory::Return(_) => "return", |
dc9dc135 XL |
1177 | ConstraintCategory::Yield => "yield", |
1178 | _ => return None, | |
1179 | }; | |
1180 | ||
1181 | // FIXME use a better heuristic than Spans | |
dfeec247 XL |
1182 | let reference_desc = if return_span == self.body.source_info(borrow.reserve_location).span { |
1183 | "reference to" | |
1184 | } else { | |
1185 | "value referencing" | |
1186 | }; | |
dc9dc135 XL |
1187 | |
1188 | let (place_desc, note) = if let Some(place_desc) = opt_place_desc { | |
e74abb32 XL |
1189 | let local_kind = if let Some(local) = borrow.borrowed_place.as_local() { |
1190 | match self.body.local_kind(local) { | |
dfeec247 XL |
1191 | LocalKind::ReturnPointer | LocalKind::Temp => { |
1192 | bug!("temporary or return pointer with a name") | |
1193 | } | |
e74abb32 | 1194 | LocalKind::Var => "local variable ", |
dfeec247 | 1195 | LocalKind::Arg if !self.upvars.is_empty() && local == Local::new(1) => { |
e74abb32 XL |
1196 | "variable captured by `move` " |
1197 | } | |
dfeec247 | 1198 | LocalKind::Arg => "function parameter ", |
dc9dc135 | 1199 | } |
e74abb32 XL |
1200 | } else { |
1201 | "local data " | |
dc9dc135 XL |
1202 | }; |
1203 | ( | |
1204 | format!("{}`{}`", local_kind, place_desc), | |
1205 | format!("`{}` is borrowed here", place_desc), | |
1206 | ) | |
1207 | } else { | |
dfeec247 XL |
1208 | let root_place = |
1209 | self.prefixes(borrow.borrowed_place.as_ref(), PrefixSet::All).last().unwrap(); | |
1210 | let local = root_place.local; | |
74b04a01 | 1211 | match self.body.local_kind(local) { |
dfeec247 XL |
1212 | LocalKind::ReturnPointer | LocalKind::Temp => { |
1213 | ("temporary value".to_string(), "temporary value created here".to_string()) | |
1214 | } | |
dc9dc135 XL |
1215 | LocalKind::Arg => ( |
1216 | "function parameter".to_string(), | |
1217 | "function parameter borrowed here".to_string(), | |
1218 | ), | |
dfeec247 XL |
1219 | LocalKind::Var => { |
1220 | ("local binding".to_string(), "local binding introduced here".to_string()) | |
1221 | } | |
dc9dc135 XL |
1222 | } |
1223 | }; | |
1224 | ||
416331ca | 1225 | let mut err = self.cannot_return_reference_to_local( |
dc9dc135 XL |
1226 | return_span, |
1227 | return_kind, | |
1228 | reference_desc, | |
1229 | &place_desc, | |
dc9dc135 XL |
1230 | ); |
1231 | ||
1232 | if return_span != borrow_span { | |
1233 | err.span_label(borrow_span, note); | |
1234 | } | |
1235 | ||
1236 | Some(err) | |
1237 | } | |
1238 | ||
1239 | fn report_escaping_closure_capture( | |
1240 | &mut self, | |
e74abb32 | 1241 | use_span: UseSpans, |
dc9dc135 XL |
1242 | var_span: Span, |
1243 | fr_name: &RegionName, | |
1244 | category: ConstraintCategory, | |
1245 | constraint_span: Span, | |
1246 | captured_var: &str, | |
1247 | ) -> DiagnosticBuilder<'cx> { | |
1248 | let tcx = self.infcx.tcx; | |
e74abb32 | 1249 | let args_span = use_span.args_or_use(); |
dc9dc135 XL |
1250 | |
1251 | let suggestion = match tcx.sess.source_map().span_to_snippet(args_span) { | |
e1599b0c XL |
1252 | Ok(mut string) => { |
1253 | if string.starts_with("async ") { | |
1254 | string.insert_str(6, "move "); | |
1255 | } else if string.starts_with("async|") { | |
1256 | string.insert_str(5, " move"); | |
1257 | } else { | |
1258 | string.insert_str(0, "move "); | |
1259 | }; | |
1260 | string | |
dfeec247 XL |
1261 | } |
1262 | Err(_) => "move |<args>| <body>".to_string(), | |
dc9dc135 | 1263 | }; |
e74abb32 XL |
1264 | let kind = match use_span.generator_kind() { |
1265 | Some(generator_kind) => match generator_kind { | |
1266 | GeneratorKind::Async(async_kind) => match async_kind { | |
1267 | AsyncGeneratorKind::Block => "async block", | |
1268 | AsyncGeneratorKind::Closure => "async closure", | |
74b04a01 | 1269 | _ => bug!("async block/closure expected, but async function found."), |
e74abb32 XL |
1270 | }, |
1271 | GeneratorKind::Gen => "generator", | |
dfeec247 | 1272 | }, |
e74abb32 XL |
1273 | None => "closure", |
1274 | }; | |
ba9703b0 XL |
1275 | |
1276 | let mut err = | |
1277 | self.cannot_capture_in_long_lived_closure(args_span, kind, captured_var, var_span); | |
dc9dc135 XL |
1278 | err.span_suggestion( |
1279 | args_span, | |
e74abb32 XL |
1280 | &format!( |
1281 | "to force the {} to take ownership of {} (and any \ | |
1282 | other referenced variables), use the `move` keyword", | |
dfeec247 | 1283 | kind, captured_var |
e74abb32 | 1284 | ), |
dc9dc135 XL |
1285 | suggestion, |
1286 | Applicability::MachineApplicable, | |
1287 | ); | |
1288 | ||
60c5eb7d | 1289 | let msg = match category { |
f035d41b | 1290 | ConstraintCategory::Return(_) | ConstraintCategory::OpaqueType => { |
ba9703b0 XL |
1291 | format!("{} is returned here", kind) |
1292 | } | |
dc9dc135 XL |
1293 | ConstraintCategory::CallArgument => { |
1294 | fr_name.highlight_region_name(&mut err); | |
60c5eb7d | 1295 | format!("function requires argument type to outlive `{}`", fr_name) |
dc9dc135 | 1296 | } |
dfeec247 XL |
1297 | _ => bug!( |
1298 | "report_escaping_closure_capture called with unexpected constraint \ | |
74b04a01 | 1299 | category: `{:?}`", |
dfeec247 XL |
1300 | category |
1301 | ), | |
60c5eb7d XL |
1302 | }; |
1303 | err.span_note(constraint_span, &msg); | |
dc9dc135 XL |
1304 | err |
1305 | } | |
1306 | ||
1307 | fn report_escaping_data( | |
1308 | &mut self, | |
1309 | borrow_span: Span, | |
1310 | name: &Option<String>, | |
1311 | upvar_span: Span, | |
1312 | upvar_name: &str, | |
1313 | escape_span: Span, | |
1314 | ) -> DiagnosticBuilder<'cx> { | |
1315 | let tcx = self.infcx.tcx; | |
1316 | ||
f9f354fc | 1317 | let (_, escapes_from) = tcx.article_and_description(self.mir_def_id.to_def_id()); |
dc9dc135 | 1318 | |
dfeec247 XL |
1319 | let mut err = |
1320 | borrowck_errors::borrowed_data_escapes_closure(tcx, escape_span, escapes_from); | |
dc9dc135 XL |
1321 | |
1322 | err.span_label( | |
1323 | upvar_span, | |
74b04a01 | 1324 | format!("`{}` declared here, outside of the {} body", upvar_name, escapes_from), |
dc9dc135 XL |
1325 | ); |
1326 | ||
dfeec247 | 1327 | err.span_label(borrow_span, format!("borrow is only valid in the {} body", escapes_from)); |
dc9dc135 XL |
1328 | |
1329 | if let Some(name) = name { | |
1330 | err.span_label( | |
1331 | escape_span, | |
1332 | format!("reference to `{}` escapes the {} body here", name, escapes_from), | |
1333 | ); | |
1334 | } else { | |
1335 | err.span_label( | |
1336 | escape_span, | |
1337 | format!("reference escapes the {} body here", escapes_from), | |
1338 | ); | |
1339 | } | |
1340 | ||
1341 | err | |
1342 | } | |
1343 | ||
1344 | fn get_moved_indexes(&mut self, location: Location, mpi: MovePathIndex) -> Vec<MoveSite> { | |
f9f354fc XL |
1345 | fn predecessor_locations( |
1346 | body: &'a mir::Body<'tcx>, | |
1347 | location: Location, | |
1348 | ) -> impl Iterator<Item = Location> + 'a { | |
1349 | if location.statement_index == 0 { | |
1350 | let predecessors = body.predecessors()[location.block].to_vec(); | |
1351 | Either::Left(predecessors.into_iter().map(move |bb| body.terminator_loc(bb))) | |
1352 | } else { | |
1353 | Either::Right(std::iter::once(Location { | |
1354 | statement_index: location.statement_index - 1, | |
1355 | ..location | |
1356 | })) | |
1357 | } | |
1358 | } | |
1359 | ||
dc9dc135 | 1360 | let mut stack = Vec::new(); |
f9f354fc | 1361 | stack.extend(predecessor_locations(self.body, location).map(|predecessor| { |
dc9dc135 XL |
1362 | let is_back_edge = location.dominates(predecessor, &self.dominators); |
1363 | (predecessor, is_back_edge) | |
1364 | })); | |
1365 | ||
1366 | let mut visited = FxHashSet::default(); | |
1367 | let mut result = vec![]; | |
1368 | ||
1369 | 'dfs: while let Some((location, is_back_edge)) = stack.pop() { | |
1370 | debug!( | |
1371 | "report_use_of_moved_or_uninitialized: (current_location={:?}, back_edge={})", | |
1372 | location, is_back_edge | |
1373 | ); | |
1374 | ||
1375 | if !visited.insert(location) { | |
1376 | continue; | |
1377 | } | |
1378 | ||
1379 | // check for moves | |
dfeec247 XL |
1380 | let stmt_kind = |
1381 | self.body[location.block].statements.get(location.statement_index).map(|s| &s.kind); | |
dc9dc135 XL |
1382 | if let Some(StatementKind::StorageDead(..)) = stmt_kind { |
1383 | // this analysis only tries to find moves explicitly | |
1384 | // written by the user, so we ignore the move-outs | |
1385 | // created by `StorageDead` and at the beginning | |
1386 | // of a function. | |
1387 | } else { | |
1388 | // If we are found a use of a.b.c which was in error, then we want to look for | |
1389 | // moves not only of a.b.c but also a.b and a. | |
1390 | // | |
1391 | // Note that the moves data already includes "parent" paths, so we don't have to | |
1392 | // worry about the other case: that is, if there is a move of a.b.c, it is already | |
1393 | // marked as a move of a.b and a as well, so we will generate the correct errors | |
1394 | // there. | |
1395 | let mut mpis = vec![mpi]; | |
1396 | let move_paths = &self.move_data.move_paths; | |
74b04a01 | 1397 | mpis.extend(move_paths[mpi].parents(move_paths).map(|(mpi, _)| mpi)); |
dc9dc135 XL |
1398 | |
1399 | for moi in &self.move_data.loc_map[location] { | |
1400 | debug!("report_use_of_moved_or_uninitialized: moi={:?}", moi); | |
1401 | if mpis.contains(&self.move_data.moves[*moi].path) { | |
1402 | debug!("report_use_of_moved_or_uninitialized: found"); | |
dfeec247 | 1403 | result.push(MoveSite { moi: *moi, traversed_back_edge: is_back_edge }); |
dc9dc135 XL |
1404 | |
1405 | // Strictly speaking, we could continue our DFS here. There may be | |
1406 | // other moves that can reach the point of error. But it is kind of | |
1407 | // confusing to highlight them. | |
1408 | // | |
1409 | // Example: | |
1410 | // | |
1411 | // ``` | |
1412 | // let a = vec![]; | |
1413 | // let b = a; | |
1414 | // let c = a; | |
1415 | // drop(a); // <-- current point of error | |
1416 | // ``` | |
1417 | // | |
1418 | // Because we stop the DFS here, we only highlight `let c = a`, | |
1419 | // and not `let b = a`. We will of course also report an error at | |
1420 | // `let c = a` which highlights `let b = a` as the move. | |
1421 | continue 'dfs; | |
1422 | } | |
1423 | } | |
1424 | } | |
1425 | ||
1426 | // check for inits | |
1427 | let mut any_match = false; | |
1428 | drop_flag_effects::for_location_inits( | |
1429 | self.infcx.tcx, | |
60c5eb7d | 1430 | &self.body, |
dc9dc135 XL |
1431 | self.move_data, |
1432 | location, | |
1433 | |m| { | |
1434 | if m == mpi { | |
1435 | any_match = true; | |
1436 | } | |
1437 | }, | |
1438 | ); | |
1439 | if any_match { | |
1440 | continue 'dfs; | |
1441 | } | |
1442 | ||
f9f354fc | 1443 | stack.extend(predecessor_locations(self.body, location).map(|predecessor| { |
dc9dc135 XL |
1444 | let back_edge = location.dominates(predecessor, &self.dominators); |
1445 | (predecessor, is_back_edge || back_edge) | |
1446 | })); | |
1447 | } | |
1448 | ||
1449 | result | |
1450 | } | |
1451 | ||
60c5eb7d | 1452 | pub(in crate::borrow_check) fn report_illegal_mutation_of_borrowed( |
dc9dc135 XL |
1453 | &mut self, |
1454 | location: Location, | |
ba9703b0 | 1455 | (place, span): (Place<'tcx>, Span), |
dc9dc135 XL |
1456 | loan: &BorrowData<'tcx>, |
1457 | ) { | |
1458 | let loan_spans = self.retrieve_borrow_spans(loan); | |
1459 | let loan_span = loan_spans.args_or_use(); | |
1460 | ||
ba9703b0 | 1461 | let descr_place = self.describe_any_place(place.as_ref()); |
dc9dc135 | 1462 | if loan.kind == BorrowKind::Shallow { |
ba9703b0 | 1463 | if let Some(section) = self.classify_immutable_section(loan.assigned_place) { |
60c5eb7d XL |
1464 | let mut err = self.cannot_mutate_in_immutable_section( |
1465 | span, | |
1466 | loan_span, | |
ba9703b0 | 1467 | &descr_place, |
60c5eb7d XL |
1468 | section, |
1469 | "assign", | |
1470 | ); | |
1471 | loan_spans.var_span_label( | |
1472 | &mut err, | |
1473 | format!("borrow occurs due to use{}", loan_spans.describe()), | |
1474 | ); | |
dc9dc135 | 1475 | |
60c5eb7d | 1476 | err.buffer(&mut self.errors_buffer); |
dc9dc135 | 1477 | |
60c5eb7d XL |
1478 | return; |
1479 | } | |
dc9dc135 XL |
1480 | } |
1481 | ||
ba9703b0 | 1482 | let mut err = self.cannot_assign_to_borrowed(span, loan_span, &descr_place); |
dc9dc135 | 1483 | |
dfeec247 XL |
1484 | loan_spans |
1485 | .var_span_label(&mut err, format!("borrow occurs due to use{}", loan_spans.describe())); | |
1486 | ||
1487 | self.explain_why_borrow_contains_point(location, loan, None).add_explanation_to_diagnostic( | |
1488 | self.infcx.tcx, | |
1489 | &self.body, | |
1490 | &self.local_names, | |
dc9dc135 | 1491 | &mut err, |
dfeec247 XL |
1492 | "", |
1493 | None, | |
dc9dc135 XL |
1494 | ); |
1495 | ||
dc9dc135 XL |
1496 | err.buffer(&mut self.errors_buffer); |
1497 | } | |
1498 | ||
1499 | /// Reports an illegal reassignment; for example, an assignment to | |
1500 | /// (part of) a non-`mut` local that occurs potentially after that | |
1501 | /// local has already been initialized. `place` is the path being | |
1502 | /// assigned; `err_place` is a place providing a reason why | |
1503 | /// `place` is not mutable (e.g., the non-`mut` local `x` in an | |
1504 | /// assignment to `x.f`). | |
60c5eb7d | 1505 | pub(in crate::borrow_check) fn report_illegal_reassignment( |
dc9dc135 XL |
1506 | &mut self, |
1507 | _location: Location, | |
ba9703b0 | 1508 | (place, span): (Place<'tcx>, Span), |
dc9dc135 | 1509 | assigned_span: Span, |
ba9703b0 | 1510 | err_place: Place<'tcx>, |
dc9dc135 | 1511 | ) { |
60c5eb7d XL |
1512 | let (from_arg, local_decl, local_name) = match err_place.as_local() { |
1513 | Some(local) => ( | |
1514 | self.body.local_kind(local) == LocalKind::Arg, | |
1515 | Some(&self.body.local_decls[local]), | |
1516 | self.local_names[local], | |
1517 | ), | |
1518 | None => (false, None, None), | |
dc9dc135 XL |
1519 | }; |
1520 | ||
1521 | // If root local is initialized immediately (everything apart from let | |
1522 | // PATTERN;) then make the error refer to that local, rather than the | |
1523 | // place being assigned later. | |
1524 | let (place_description, assigned_span) = match local_decl { | |
ba9703b0 | 1525 | Some(LocalDecl { |
dfeec247 | 1526 | local_info: |
f9f354fc | 1527 | Some(box LocalInfo::User( |
ba9703b0 XL |
1528 | ClearCrossCrate::Clear |
1529 | | ClearCrossCrate::Set(BindingForm::Var(VarBindingForm { | |
1530 | opt_match_place: None, | |
1531 | .. | |
1532 | })), | |
f9f354fc XL |
1533 | )) |
1534 | | Some(box LocalInfo::StaticRef { .. }) | |
1535 | | None, | |
dc9dc135 XL |
1536 | .. |
1537 | }) | |
ba9703b0 XL |
1538 | | None => (self.describe_any_place(place.as_ref()), assigned_span), |
1539 | Some(decl) => (self.describe_any_place(err_place.as_ref()), decl.source_info.span), | |
dc9dc135 XL |
1540 | }; |
1541 | ||
ba9703b0 | 1542 | let mut err = self.cannot_reassign_immutable(span, &place_description, from_arg); |
dc9dc135 XL |
1543 | let msg = if from_arg { |
1544 | "cannot assign to immutable argument" | |
1545 | } else { | |
1546 | "cannot assign twice to immutable variable" | |
1547 | }; | |
1548 | if span != assigned_span { | |
1549 | if !from_arg { | |
ba9703b0 | 1550 | err.span_label(assigned_span, format!("first assignment to {}", place_description)); |
dc9dc135 XL |
1551 | } |
1552 | } | |
1553 | if let Some(decl) = local_decl { | |
60c5eb7d | 1554 | if let Some(name) = local_name { |
dc9dc135 XL |
1555 | if decl.can_be_made_mutable() { |
1556 | err.span_suggestion( | |
1557 | decl.source_info.span, | |
1558 | "make this binding mutable", | |
1559 | format!("mut {}", name), | |
1560 | Applicability::MachineApplicable, | |
1561 | ); | |
1562 | } | |
1563 | } | |
1564 | } | |
1565 | err.span_label(span, msg); | |
1566 | err.buffer(&mut self.errors_buffer); | |
1567 | } | |
1568 | ||
74b04a01 | 1569 | fn classify_drop_access_kind(&self, place: PlaceRef<'tcx>) -> StorageDeadOrDrop<'tcx> { |
dc9dc135 | 1570 | let tcx = self.infcx.tcx; |
416331ca | 1571 | match place.projection { |
dfeec247 | 1572 | [] => StorageDeadOrDrop::LocalStorageDead, |
e1599b0c XL |
1573 | [proj_base @ .., elem] => { |
1574 | // FIXME(spastorino) make this iterate | |
416331ca | 1575 | let base_access = self.classify_drop_access_kind(PlaceRef { |
dfeec247 | 1576 | local: place.local, |
e1599b0c | 1577 | projection: proj_base, |
416331ca | 1578 | }); |
dc9dc135 XL |
1579 | match elem { |
1580 | ProjectionElem::Deref => match base_access { | |
1581 | StorageDeadOrDrop::LocalStorageDead | |
1582 | | StorageDeadOrDrop::BoxedStorageDead => { | |
1583 | assert!( | |
f9f354fc | 1584 | Place::ty_from(place.local, proj_base, self.body, tcx).ty.is_box(), |
dc9dc135 XL |
1585 | "Drop of value behind a reference or raw pointer" |
1586 | ); | |
1587 | StorageDeadOrDrop::BoxedStorageDead | |
1588 | } | |
1589 | StorageDeadOrDrop::Destructor(_) => base_access, | |
1590 | }, | |
1591 | ProjectionElem::Field(..) | ProjectionElem::Downcast(..) => { | |
f9f354fc | 1592 | let base_ty = Place::ty_from(place.local, proj_base, self.body, tcx).ty; |
e74abb32 | 1593 | match base_ty.kind { |
dc9dc135 XL |
1594 | ty::Adt(def, _) if def.has_dtor(tcx) => { |
1595 | // Report the outermost adt with a destructor | |
1596 | match base_access { | |
1597 | StorageDeadOrDrop::Destructor(_) => base_access, | |
1598 | StorageDeadOrDrop::LocalStorageDead | |
1599 | | StorageDeadOrDrop::BoxedStorageDead => { | |
1600 | StorageDeadOrDrop::Destructor(base_ty) | |
1601 | } | |
1602 | } | |
1603 | } | |
1604 | _ => base_access, | |
1605 | } | |
1606 | } | |
1607 | ||
1608 | ProjectionElem::ConstantIndex { .. } | |
1609 | | ProjectionElem::Subslice { .. } | |
1610 | | ProjectionElem::Index(_) => base_access, | |
1611 | } | |
1612 | } | |
1613 | } | |
1614 | } | |
1615 | ||
60c5eb7d | 1616 | /// Describe the reason for the fake borrow that was assigned to `place`. |
ba9703b0 XL |
1617 | fn classify_immutable_section(&self, place: Place<'tcx>) -> Option<&'static str> { |
1618 | use rustc_middle::mir::visit::Visitor; | |
1619 | struct FakeReadCauseFinder<'tcx> { | |
1620 | place: Place<'tcx>, | |
60c5eb7d XL |
1621 | cause: Option<FakeReadCause>, |
1622 | } | |
ba9703b0 | 1623 | impl<'tcx> Visitor<'tcx> for FakeReadCauseFinder<'tcx> { |
60c5eb7d XL |
1624 | fn visit_statement(&mut self, statement: &Statement<'tcx>, _: Location) { |
1625 | match statement { | |
ba9703b0 XL |
1626 | Statement { kind: StatementKind::FakeRead(cause, box place), .. } |
1627 | if *place == self.place => | |
dfeec247 | 1628 | { |
60c5eb7d XL |
1629 | self.cause = Some(*cause); |
1630 | } | |
1631 | _ => (), | |
1632 | } | |
1633 | } | |
1634 | } | |
1635 | let mut visitor = FakeReadCauseFinder { place, cause: None }; | |
ba9703b0 | 1636 | visitor.visit_body(&self.body); |
60c5eb7d XL |
1637 | match visitor.cause { |
1638 | Some(FakeReadCause::ForMatchGuard) => Some("match guard"), | |
1639 | Some(FakeReadCause::ForIndex) => Some("indexing expression"), | |
1640 | _ => None, | |
1641 | } | |
1642 | } | |
1643 | ||
dc9dc135 XL |
1644 | /// Annotate argument and return type of function and closure with (synthesized) lifetime for |
1645 | /// borrow of local value that does not live long enough. | |
1646 | fn annotate_argument_and_return_for_borrow( | |
1647 | &self, | |
1648 | borrow: &BorrowData<'tcx>, | |
1649 | ) -> Option<AnnotatedBorrowFnSignature<'tcx>> { | |
1650 | // Define a fallback for when we can't match a closure. | |
1651 | let fallback = || { | |
f9f354fc | 1652 | let is_closure = self.infcx.tcx.is_closure(self.mir_def_id.to_def_id()); |
dc9dc135 XL |
1653 | if is_closure { |
1654 | None | |
1655 | } else { | |
1656 | let ty = self.infcx.tcx.type_of(self.mir_def_id); | |
e74abb32 | 1657 | match ty.kind { |
f9f354fc XL |
1658 | ty::FnDef(_, _) | ty::FnPtr(_) => self.annotate_fn_sig( |
1659 | self.mir_def_id.to_def_id(), | |
1660 | self.infcx.tcx.fn_sig(self.mir_def_id), | |
1661 | ), | |
dc9dc135 XL |
1662 | _ => None, |
1663 | } | |
1664 | } | |
1665 | }; | |
1666 | ||
1667 | // In order to determine whether we need to annotate, we need to check whether the reserve | |
1668 | // place was an assignment into a temporary. | |
1669 | // | |
1670 | // If it was, we check whether or not that temporary is eventually assigned into the return | |
1671 | // place. If it was, we can add annotations about the function's return type and arguments | |
1672 | // and it'll make sense. | |
1673 | let location = borrow.reserve_location; | |
dfeec247 XL |
1674 | debug!("annotate_argument_and_return_for_borrow: location={:?}", location); |
1675 | if let Some(&Statement { kind: StatementKind::Assign(box (ref reservation, _)), .. }) = | |
1676 | &self.body[location.block].statements.get(location.statement_index) | |
dc9dc135 | 1677 | { |
dfeec247 | 1678 | debug!("annotate_argument_and_return_for_borrow: reservation={:?}", reservation); |
dc9dc135 | 1679 | // Check that the initial assignment of the reserve location is into a temporary. |
e74abb32 XL |
1680 | let mut target = match reservation.as_local() { |
1681 | Some(local) if self.body.local_kind(local) == LocalKind::Temp => local, | |
dc9dc135 XL |
1682 | _ => return None, |
1683 | }; | |
1684 | ||
1685 | // Next, look through the rest of the block, checking if we are assigning the | |
1686 | // `target` (that is, the place that contains our borrow) to anything. | |
1687 | let mut annotated_closure = None; | |
dfeec247 | 1688 | for stmt in &self.body[location.block].statements[location.statement_index + 1..] { |
dc9dc135 XL |
1689 | debug!( |
1690 | "annotate_argument_and_return_for_borrow: target={:?} stmt={:?}", | |
1691 | target, stmt | |
1692 | ); | |
dfeec247 | 1693 | if let StatementKind::Assign(box (place, rvalue)) = &stmt.kind { |
e74abb32 XL |
1694 | if let Some(assigned_to) = place.as_local() { |
1695 | debug!( | |
1696 | "annotate_argument_and_return_for_borrow: assigned_to={:?} \ | |
1697 | rvalue={:?}", | |
1698 | assigned_to, rvalue | |
1699 | ); | |
1700 | // Check if our `target` was captured by a closure. | |
1701 | if let Rvalue::Aggregate( | |
1702 | box AggregateKind::Closure(def_id, substs), | |
1703 | operands, | |
1704 | ) = rvalue | |
1705 | { | |
1706 | for operand in operands { | |
1707 | let assigned_from = match operand { | |
1708 | Operand::Copy(assigned_from) | Operand::Move(assigned_from) => { | |
1709 | assigned_from | |
1710 | } | |
1711 | _ => continue, | |
1712 | }; | |
1713 | debug!( | |
1714 | "annotate_argument_and_return_for_borrow: assigned_from={:?}", | |
dc9dc135 | 1715 | assigned_from |
e74abb32 | 1716 | ); |
dc9dc135 | 1717 | |
e74abb32 XL |
1718 | // Find the local from the operand. |
1719 | let assigned_from_local = match assigned_from.local_or_deref_local() | |
1720 | { | |
1721 | Some(local) => local, | |
1722 | None => continue, | |
1723 | }; | |
dc9dc135 | 1724 | |
e74abb32 XL |
1725 | if assigned_from_local != target { |
1726 | continue; | |
1727 | } | |
dc9dc135 | 1728 | |
e74abb32 XL |
1729 | // If a closure captured our `target` and then assigned |
1730 | // into a place then we should annotate the closure in | |
1731 | // case it ends up being assigned into the return place. | |
ba9703b0 XL |
1732 | annotated_closure = |
1733 | self.annotate_fn_sig(*def_id, substs.as_closure().sig()); | |
e74abb32 XL |
1734 | debug!( |
1735 | "annotate_argument_and_return_for_borrow: \ | |
1736 | annotated_closure={:?} assigned_from_local={:?} \ | |
1737 | assigned_to={:?}", | |
1738 | annotated_closure, assigned_from_local, assigned_to | |
1739 | ); | |
1740 | ||
1741 | if assigned_to == mir::RETURN_PLACE { | |
1742 | // If it was assigned directly into the return place, then | |
1743 | // return now. | |
1744 | return annotated_closure; | |
1745 | } else { | |
1746 | // Otherwise, update the target. | |
1747 | target = assigned_to; | |
1748 | } | |
dc9dc135 | 1749 | } |
dc9dc135 | 1750 | |
e74abb32 XL |
1751 | // If none of our closure's operands matched, then skip to the next |
1752 | // statement. | |
1753 | continue; | |
1754 | } | |
dc9dc135 | 1755 | |
e74abb32 XL |
1756 | // Otherwise, look at other types of assignment. |
1757 | let assigned_from = match rvalue { | |
1758 | Rvalue::Ref(_, _, assigned_from) => assigned_from, | |
1759 | Rvalue::Use(operand) => match operand { | |
1760 | Operand::Copy(assigned_from) | Operand::Move(assigned_from) => { | |
1761 | assigned_from | |
1762 | } | |
1763 | _ => continue, | |
1764 | }, | |
dc9dc135 | 1765 | _ => continue, |
e74abb32 XL |
1766 | }; |
1767 | debug!( | |
1768 | "annotate_argument_and_return_for_borrow: \ | |
1769 | assigned_from={:?}", | |
1770 | assigned_from, | |
1771 | ); | |
dc9dc135 | 1772 | |
e74abb32 XL |
1773 | // Find the local from the rvalue. |
1774 | let assigned_from_local = match assigned_from.local_or_deref_local() { | |
1775 | Some(local) => local, | |
1776 | None => continue, | |
1777 | }; | |
1778 | debug!( | |
1779 | "annotate_argument_and_return_for_borrow: \ | |
1780 | assigned_from_local={:?}", | |
1781 | assigned_from_local, | |
1782 | ); | |
dc9dc135 | 1783 | |
e74abb32 XL |
1784 | // Check if our local matches the target - if so, we've assigned our |
1785 | // borrow to a new place. | |
1786 | if assigned_from_local != target { | |
1787 | continue; | |
1788 | } | |
dc9dc135 | 1789 | |
e74abb32 XL |
1790 | // If we assigned our `target` into a new place, then we should |
1791 | // check if it was the return place. | |
1792 | debug!( | |
1793 | "annotate_argument_and_return_for_borrow: \ | |
1794 | assigned_from_local={:?} assigned_to={:?}", | |
1795 | assigned_from_local, assigned_to | |
1796 | ); | |
1797 | if assigned_to == mir::RETURN_PLACE { | |
1798 | // If it was then return the annotated closure if there was one, | |
1799 | // else, annotate this function. | |
1800 | return annotated_closure.or_else(fallback); | |
1801 | } | |
dc9dc135 | 1802 | |
e74abb32 XL |
1803 | // If we didn't assign into the return place, then we just update |
1804 | // the target. | |
1805 | target = assigned_to; | |
1806 | } | |
dc9dc135 XL |
1807 | } |
1808 | } | |
1809 | ||
1810 | // Check the terminator if we didn't find anything in the statements. | |
1811 | let terminator = &self.body[location.block].terminator(); | |
1812 | debug!( | |
1813 | "annotate_argument_and_return_for_borrow: target={:?} terminator={:?}", | |
1814 | target, terminator | |
1815 | ); | |
dfeec247 XL |
1816 | if let TerminatorKind::Call { destination: Some((place, _)), args, .. } = |
1817 | &terminator.kind | |
dc9dc135 | 1818 | { |
e74abb32 | 1819 | if let Some(assigned_to) = place.as_local() { |
dc9dc135 | 1820 | debug!( |
e74abb32 XL |
1821 | "annotate_argument_and_return_for_borrow: assigned_to={:?} args={:?}", |
1822 | assigned_to, args | |
dc9dc135 | 1823 | ); |
e74abb32 XL |
1824 | for operand in args { |
1825 | let assigned_from = match operand { | |
1826 | Operand::Copy(assigned_from) | Operand::Move(assigned_from) => { | |
1827 | assigned_from | |
1828 | } | |
1829 | _ => continue, | |
1830 | }; | |
dc9dc135 | 1831 | debug!( |
e74abb32 XL |
1832 | "annotate_argument_and_return_for_borrow: assigned_from={:?}", |
1833 | assigned_from, | |
dc9dc135 XL |
1834 | ); |
1835 | ||
e74abb32 XL |
1836 | if let Some(assigned_from_local) = assigned_from.local_or_deref_local() { |
1837 | debug!( | |
1838 | "annotate_argument_and_return_for_borrow: assigned_from_local={:?}", | |
1839 | assigned_from_local, | |
1840 | ); | |
1841 | ||
1842 | if assigned_to == mir::RETURN_PLACE && assigned_from_local == target { | |
1843 | return annotated_closure.or_else(fallback); | |
1844 | } | |
dc9dc135 XL |
1845 | } |
1846 | } | |
1847 | } | |
1848 | } | |
1849 | } | |
1850 | ||
1851 | // If we haven't found an assignment into the return place, then we need not add | |
1852 | // any annotations. | |
1853 | debug!("annotate_argument_and_return_for_borrow: none found"); | |
1854 | None | |
1855 | } | |
1856 | ||
1857 | /// Annotate the first argument and return type of a function signature if they are | |
1858 | /// references. | |
1859 | fn annotate_fn_sig( | |
1860 | &self, | |
1861 | did: DefId, | |
1862 | sig: ty::PolyFnSig<'tcx>, | |
1863 | ) -> Option<AnnotatedBorrowFnSignature<'tcx>> { | |
1864 | debug!("annotate_fn_sig: did={:?} sig={:?}", did, sig); | |
1865 | let is_closure = self.infcx.tcx.is_closure(did); | |
3dfed10e | 1866 | let fn_hir_id = self.infcx.tcx.hir().local_def_id_to_hir_id(did.as_local()?); |
dc9dc135 XL |
1867 | let fn_decl = self.infcx.tcx.hir().fn_decl_by_hir_id(fn_hir_id)?; |
1868 | ||
1869 | // We need to work out which arguments to highlight. We do this by looking | |
1870 | // at the return type, where there are three cases: | |
1871 | // | |
1872 | // 1. If there are named arguments, then we should highlight the return type and | |
1873 | // highlight any of the arguments that are also references with that lifetime. | |
1874 | // If there are no arguments that have the same lifetime as the return type, | |
1875 | // then don't highlight anything. | |
1876 | // 2. The return type is a reference with an anonymous lifetime. If this is | |
1877 | // the case, then we can take advantage of (and teach) the lifetime elision | |
1878 | // rules. | |
1879 | // | |
1880 | // We know that an error is being reported. So the arguments and return type | |
1881 | // must satisfy the elision rules. Therefore, if there is a single argument | |
1882 | // then that means the return type and first (and only) argument have the same | |
1883 | // lifetime and the borrow isn't meeting that, we can highlight the argument | |
1884 | // and return type. | |
1885 | // | |
1886 | // If there are multiple arguments then the first argument must be self (else | |
1887 | // it would not satisfy the elision rules), so we can highlight self and the | |
1888 | // return type. | |
1889 | // 3. The return type is not a reference. In this case, we don't highlight | |
1890 | // anything. | |
1891 | let return_ty = sig.output(); | |
e74abb32 | 1892 | match return_ty.skip_binder().kind { |
dc9dc135 XL |
1893 | ty::Ref(return_region, _, _) if return_region.has_name() && !is_closure => { |
1894 | // This is case 1 from above, return type is a named reference so we need to | |
1895 | // search for relevant arguments. | |
1896 | let mut arguments = Vec::new(); | |
1897 | for (index, argument) in sig.inputs().skip_binder().iter().enumerate() { | |
e74abb32 | 1898 | if let ty::Ref(argument_region, _, _) = argument.kind { |
dc9dc135 | 1899 | if argument_region == return_region { |
ba9703b0 | 1900 | // Need to use the `rustc_middle::ty` types to compare against the |
dfeec247 | 1901 | // `return_region`. Then use the `rustc_hir` type to get only |
dc9dc135 | 1902 | // the lifetime span. |
e74abb32 | 1903 | if let hir::TyKind::Rptr(lifetime, _) = &fn_decl.inputs[index].kind { |
dc9dc135 XL |
1904 | // With access to the lifetime, we can get |
1905 | // the span of it. | |
1906 | arguments.push((*argument, lifetime.span)); | |
1907 | } else { | |
1908 | bug!("ty type is a ref but hir type is not"); | |
1909 | } | |
1910 | } | |
1911 | } | |
1912 | } | |
1913 | ||
1914 | // We need to have arguments. This shouldn't happen, but it's worth checking. | |
1915 | if arguments.is_empty() { | |
1916 | return None; | |
1917 | } | |
1918 | ||
1919 | // We use a mix of the HIR and the Ty types to get information | |
1920 | // as the HIR doesn't have full types for closure arguments. | |
f035d41b | 1921 | let return_ty = sig.output().skip_binder(); |
dc9dc135 | 1922 | let mut return_span = fn_decl.output.span(); |
74b04a01 | 1923 | if let hir::FnRetTy::Return(ty) = &fn_decl.output { |
e74abb32 | 1924 | if let hir::TyKind::Rptr(lifetime, _) = ty.kind { |
dc9dc135 XL |
1925 | return_span = lifetime.span; |
1926 | } | |
1927 | } | |
1928 | ||
1929 | Some(AnnotatedBorrowFnSignature::NamedFunction { | |
1930 | arguments, | |
1931 | return_ty, | |
1932 | return_span, | |
1933 | }) | |
1934 | } | |
1935 | ty::Ref(_, _, _) if is_closure => { | |
1936 | // This is case 2 from above but only for closures, return type is anonymous | |
1937 | // reference so we select | |
1938 | // the first argument. | |
1939 | let argument_span = fn_decl.inputs.first()?.span; | |
1940 | let argument_ty = sig.inputs().skip_binder().first()?; | |
1941 | ||
1942 | // Closure arguments are wrapped in a tuple, so we need to get the first | |
1943 | // from that. | |
e74abb32 | 1944 | if let ty::Tuple(elems) = argument_ty.kind { |
dc9dc135 | 1945 | let argument_ty = elems.first()?.expect_ty(); |
e74abb32 | 1946 | if let ty::Ref(_, _, _) = argument_ty.kind { |
dc9dc135 XL |
1947 | return Some(AnnotatedBorrowFnSignature::Closure { |
1948 | argument_ty, | |
1949 | argument_span, | |
1950 | }); | |
1951 | } | |
1952 | } | |
1953 | ||
1954 | None | |
1955 | } | |
1956 | ty::Ref(_, _, _) => { | |
1957 | // This is also case 2 from above but for functions, return type is still an | |
1958 | // anonymous reference so we select the first argument. | |
1959 | let argument_span = fn_decl.inputs.first()?.span; | |
1960 | let argument_ty = sig.inputs().skip_binder().first()?; | |
1961 | ||
1962 | let return_span = fn_decl.output.span(); | |
f035d41b | 1963 | let return_ty = sig.output().skip_binder(); |
dc9dc135 XL |
1964 | |
1965 | // We expect the first argument to be a reference. | |
e74abb32 | 1966 | match argument_ty.kind { |
dc9dc135 XL |
1967 | ty::Ref(_, _, _) => {} |
1968 | _ => return None, | |
1969 | } | |
1970 | ||
1971 | Some(AnnotatedBorrowFnSignature::AnonymousFunction { | |
1972 | argument_ty, | |
1973 | argument_span, | |
1974 | return_ty, | |
1975 | return_span, | |
1976 | }) | |
1977 | } | |
1978 | _ => { | |
1979 | // This is case 3 from above, return type is not a reference so don't highlight | |
1980 | // anything. | |
1981 | None | |
1982 | } | |
1983 | } | |
1984 | } | |
1985 | } | |
1986 | ||
1987 | #[derive(Debug)] | |
1988 | enum AnnotatedBorrowFnSignature<'tcx> { | |
1989 | NamedFunction { | |
1990 | arguments: Vec<(Ty<'tcx>, Span)>, | |
1991 | return_ty: Ty<'tcx>, | |
1992 | return_span: Span, | |
1993 | }, | |
1994 | AnonymousFunction { | |
1995 | argument_ty: Ty<'tcx>, | |
1996 | argument_span: Span, | |
1997 | return_ty: Ty<'tcx>, | |
1998 | return_span: Span, | |
1999 | }, | |
2000 | Closure { | |
2001 | argument_ty: Ty<'tcx>, | |
2002 | argument_span: Span, | |
2003 | }, | |
2004 | } | |
2005 | ||
2006 | impl<'tcx> AnnotatedBorrowFnSignature<'tcx> { | |
2007 | /// Annotate the provided diagnostic with information about borrow from the fn signature that | |
2008 | /// helps explain. | |
60c5eb7d | 2009 | pub(in crate::borrow_check) fn emit( |
dc9dc135 XL |
2010 | &self, |
2011 | cx: &mut MirBorrowckCtxt<'_, 'tcx>, | |
2012 | diag: &mut DiagnosticBuilder<'_>, | |
2013 | ) -> String { | |
2014 | match self { | |
dfeec247 | 2015 | AnnotatedBorrowFnSignature::Closure { argument_ty, argument_span } => { |
dc9dc135 XL |
2016 | diag.span_label( |
2017 | *argument_span, | |
2018 | format!("has type `{}`", cx.get_name_for_ty(argument_ty, 0)), | |
2019 | ); | |
2020 | ||
2021 | cx.get_region_name_for_ty(argument_ty, 0) | |
2022 | } | |
2023 | AnnotatedBorrowFnSignature::AnonymousFunction { | |
2024 | argument_ty, | |
2025 | argument_span, | |
2026 | return_ty, | |
2027 | return_span, | |
2028 | } => { | |
2029 | let argument_ty_name = cx.get_name_for_ty(argument_ty, 0); | |
2030 | diag.span_label(*argument_span, format!("has type `{}`", argument_ty_name)); | |
2031 | ||
2032 | let return_ty_name = cx.get_name_for_ty(return_ty, 0); | |
2033 | let types_equal = return_ty_name == argument_ty_name; | |
2034 | diag.span_label( | |
2035 | *return_span, | |
2036 | format!( | |
2037 | "{}has type `{}`", | |
2038 | if types_equal { "also " } else { "" }, | |
2039 | return_ty_name, | |
2040 | ), | |
2041 | ); | |
2042 | ||
2043 | diag.note( | |
2044 | "argument and return type have the same lifetime due to lifetime elision rules", | |
2045 | ); | |
2046 | diag.note( | |
2047 | "to learn more, visit <https://doc.rust-lang.org/book/ch10-03-\ | |
2048 | lifetime-syntax.html#lifetime-elision>", | |
2049 | ); | |
2050 | ||
2051 | cx.get_region_name_for_ty(return_ty, 0) | |
2052 | } | |
dfeec247 | 2053 | AnnotatedBorrowFnSignature::NamedFunction { arguments, return_ty, return_span } => { |
dc9dc135 XL |
2054 | // Region of return type and arguments checked to be the same earlier. |
2055 | let region_name = cx.get_region_name_for_ty(return_ty, 0); | |
2056 | for (_, argument_span) in arguments { | |
2057 | diag.span_label(*argument_span, format!("has lifetime `{}`", region_name)); | |
2058 | } | |
2059 | ||
dfeec247 | 2060 | diag.span_label(*return_span, format!("also has lifetime `{}`", region_name,)); |
dc9dc135 XL |
2061 | |
2062 | diag.help(&format!( | |
2063 | "use data from the highlighted arguments which match the `{}` lifetime of \ | |
2064 | the return type", | |
2065 | region_name, | |
2066 | )); | |
2067 | ||
2068 | region_name | |
2069 | } | |
2070 | } | |
2071 | } | |
2072 | } |