compiler/rustc_borrowck/src/borrowck_errors.rs

   1 use rustc_errors::{struct_span_err, DiagnosticBuilder, DiagnosticId, ErrorGuaranteed, MultiSpan};
   2 use rustc_middle::ty::{self, Ty, TyCtxt};
   3 use rustc_span::Span;
   4
   5 impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
   6     crate fn cannot_move_when_borrowed(
   7         &self,
   8         span: Span,
   9         desc: &str,
  10     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
  11         struct_span_err!(self, span, E0505, "cannot move out of {} because it is borrowed", desc,)
  12     }
  13
  14     crate fn cannot_use_when_mutably_borrowed(
  15         &self,
  16         span: Span,
  17         desc: &str,
  18         borrow_span: Span,
  19         borrow_desc: &str,
  20     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
  21         let mut err = struct_span_err!(
  22             self,
  23             span,
  24             E0503,
  25             "cannot use {} because it was mutably borrowed",
  26             desc,
  27         );
  28
  29         err.span_label(borrow_span, format!("borrow of {} occurs here", borrow_desc));
  30         err.span_label(span, format!("use of borrowed {}", borrow_desc));
  31         err
  32     }
  33
  34     crate fn cannot_act_on_uninitialized_variable(
  35         &self,
  36         span: Span,
  37         verb: &str,
  38         desc: &str,
  39     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
  40         struct_span_err!(
  41             self,
  42             span,
  43             E0381,
  44             "{} of possibly-uninitialized variable: `{}`",
  45             verb,
  46             desc,
  47         )
  48     }
  49
  50     crate fn cannot_mutably_borrow_multiply(
  51         &self,
  52         new_loan_span: Span,
  53         desc: &str,
  54         opt_via: &str,
  55         old_loan_span: Span,
  56         old_opt_via: &str,
  57         old_load_end_span: Option<Span>,
  58     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
  59         let via =
  60             |msg: &str| if msg.is_empty() { "".to_string() } else { format!(" (via {})", msg) };
  61         let mut err = struct_span_err!(
  62             self,
  63             new_loan_span,
  64             E0499,
  65             "cannot borrow {}{} as mutable more than once at a time",
  66             desc,
  67             via(opt_via),
  68         );
  69         if old_loan_span == new_loan_span {
  70             // Both borrows are happening in the same place
  71             // Meaning the borrow is occurring in a loop
  72             err.span_label(
  73                 new_loan_span,
  74                 format!(
  75                     "{}{} was mutably borrowed here in the previous iteration of the loop{}",
  76                     desc,
  77                     via(opt_via),
  78                     opt_via,
  79                 ),
  80             );
  81             if let Some(old_load_end_span) = old_load_end_span {
  82                 err.span_label(old_load_end_span, "mutable borrow ends here");
  83             }
  84         } else {
  85             err.span_label(
  86                 old_loan_span,
  87                 format!("first mutable borrow occurs here{}", via(old_opt_via)),
  88             );
  89             err.span_label(
  90                 new_loan_span,
  91                 format!("second mutable borrow occurs here{}", via(opt_via)),
  92             );
  93             if let Some(old_load_end_span) = old_load_end_span {
  94                 err.span_label(old_load_end_span, "first borrow ends here");
  95             }
  96         }
  97         err
  98     }
  99
 100     crate fn cannot_uniquely_borrow_by_two_closures(
 101         &self,
 102         new_loan_span: Span,
 103         desc: &str,
 104         old_loan_span: Span,
 105         old_load_end_span: Option<Span>,
 106     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 107         let mut err = struct_span_err!(
 108             self,
 109             new_loan_span,
 110             E0524,
 111             "two closures require unique access to {} at the same time",
 112             desc,
 113         );
 114         if old_loan_span == new_loan_span {
 115             err.span_label(
 116                 old_loan_span,
 117                 "closures are constructed here in different iterations of loop",
 118             );
 119         } else {
 120             err.span_label(old_loan_span, "first closure is constructed here");
 121             err.span_label(new_loan_span, "second closure is constructed here");
 122         }
 123         if let Some(old_load_end_span) = old_load_end_span {
 124             err.span_label(old_load_end_span, "borrow from first closure ends here");
 125         }
 126         err
 127     }
 128
 129     crate fn cannot_uniquely_borrow_by_one_closure(
 130         &self,
 131         new_loan_span: Span,
 132         container_name: &str,
 133         desc_new: &str,
 134         opt_via: &str,
 135         old_loan_span: Span,
 136         noun_old: &str,
 137         old_opt_via: &str,
 138         previous_end_span: Option<Span>,
 139     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 140         let mut err = struct_span_err!(
 141             self,
 142             new_loan_span,
 143             E0500,
 144             "closure requires unique access to {} but {} is already borrowed{}",
 145             desc_new,
 146             noun_old,
 147             old_opt_via,
 148         );
 149         err.span_label(
 150             new_loan_span,
 151             format!("{} construction occurs here{}", container_name, opt_via),
 152         );
 153         err.span_label(old_loan_span, format!("borrow occurs here{}", old_opt_via));
 154         if let Some(previous_end_span) = previous_end_span {
 155             err.span_label(previous_end_span, "borrow ends here");
 156         }
 157         err
 158     }
 159
 160     crate fn cannot_reborrow_already_uniquely_borrowed(
 161         &self,
 162         new_loan_span: Span,
 163         container_name: &str,
 164         desc_new: &str,
 165         opt_via: &str,
 166         kind_new: &str,
 167         old_loan_span: Span,
 168         old_opt_via: &str,
 169         previous_end_span: Option<Span>,
 170         second_borrow_desc: &str,
 171     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 172         let mut err = struct_span_err!(
 173             self,
 174             new_loan_span,
 175             E0501,
 176             "cannot borrow {}{} as {} because previous closure \
 177              requires unique access",
 178             desc_new,
 179             opt_via,
 180             kind_new,
 181         );
 182         err.span_label(
 183             new_loan_span,
 184             format!("{}borrow occurs here{}", second_borrow_desc, opt_via),
 185         );
 186         err.span_label(
 187             old_loan_span,
 188             format!("{} construction occurs here{}", container_name, old_opt_via),
 189         );
 190         if let Some(previous_end_span) = previous_end_span {
 191             err.span_label(previous_end_span, "borrow from closure ends here");
 192         }
 193         err
 194     }
 195
 196     crate fn cannot_reborrow_already_borrowed(
 197         &self,
 198         span: Span,
 199         desc_new: &str,
 200         msg_new: &str,
 201         kind_new: &str,
 202         old_span: Span,
 203         noun_old: &str,
 204         kind_old: &str,
 205         msg_old: &str,
 206         old_load_end_span: Option<Span>,
 207     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 208         let via =
 209             |msg: &str| if msg.is_empty() { "".to_string() } else { format!(" (via {})", msg) };
 210         let mut err = struct_span_err!(
 211             self,
 212             span,
 213             E0502,
 214             "cannot borrow {}{} as {} because {} is also borrowed as {}{}",
 215             desc_new,
 216             via(msg_new),
 217             kind_new,
 218             noun_old,
 219             kind_old,
 220             via(msg_old),
 221         );
 222
 223         if msg_new == "" {
 224             // If `msg_new` is empty, then this isn't a borrow of a union field.
 225             err.span_label(span, format!("{} borrow occurs here", kind_new));
 226             err.span_label(old_span, format!("{} borrow occurs here", kind_old));
 227         } else {
 228             // If `msg_new` isn't empty, then this a borrow of a union field.
 229             err.span_label(
 230                 span,
 231                 format!(
 232                     "{} borrow of {} -- which overlaps with {} -- occurs here",
 233                     kind_new, msg_new, msg_old,
 234                 ),
 235             );
 236             err.span_label(old_span, format!("{} borrow occurs here{}", kind_old, via(msg_old)));
 237         }
 238
 239         if let Some(old_load_end_span) = old_load_end_span {
 240             err.span_label(old_load_end_span, format!("{} borrow ends here", kind_old));
 241         }
 242         err
 243     }
 244
 245     crate fn cannot_assign_to_borrowed(
 246         &self,
 247         span: Span,
 248         borrow_span: Span,
 249         desc: &str,
 250     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 251         let mut err = struct_span_err!(
 252             self,
 253             span,
 254             E0506,
 255             "cannot assign to {} because it is borrowed",
 256             desc,
 257         );
 258
 259         err.span_label(borrow_span, format!("borrow of {} occurs here", desc));
 260         err.span_label(span, format!("assignment to borrowed {} occurs here", desc));
 261         err
 262     }
 263
 264     crate fn cannot_reassign_immutable(
 265         &self,
 266         span: Span,
 267         desc: &str,
 268         is_arg: bool,
 269     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 270         let msg = if is_arg { "to immutable argument" } else { "twice to immutable variable" };
 271         struct_span_err!(self, span, E0384, "cannot assign {} {}", msg, desc)
 272     }
 273
 274     crate fn cannot_assign(
 275         &self,
 276         span: Span,
 277         desc: &str,
 278     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 279         struct_span_err!(self, span, E0594, "cannot assign to {}", desc)
 280     }
 281
 282     crate fn cannot_move_out_of(
 283         &self,
 284         move_from_span: Span,
 285         move_from_desc: &str,
 286     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 287         struct_span_err!(self, move_from_span, E0507, "cannot move out of {}", move_from_desc,)
 288     }
 289
 290     /// Signal an error due to an attempt to move out of the interior
 291     /// of an array or slice. `is_index` is None when error origin
 292     /// didn't capture whether there was an indexing operation or not.
 293     crate fn cannot_move_out_of_interior_noncopy(
 294         &self,
 295         move_from_span: Span,
 296         ty: Ty<'_>,
 297         is_index: Option<bool>,
 298     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 299         let type_name = match (&ty.kind(), is_index) {
 300             (&ty::Array(_, _), Some(true)) | (&ty::Array(_, _), None) => "array",
 301             (&ty::Slice(_), _) => "slice",
 302             _ => span_bug!(move_from_span, "this path should not cause illegal move"),
 303         };
 304         let mut err = struct_span_err!(
 305             self,
 306             move_from_span,
 307             E0508,
 308             "cannot move out of type `{}`, a non-copy {}",
 309             ty,
 310             type_name,
 311         );
 312         err.span_label(move_from_span, "cannot move out of here");
 313         err
 314     }
 315
 316     crate fn cannot_move_out_of_interior_of_drop(
 317         &self,
 318         move_from_span: Span,
 319         container_ty: Ty<'_>,
 320     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 321         let mut err = struct_span_err!(
 322             self,
 323             move_from_span,
 324             E0509,
 325             "cannot move out of type `{}`, which implements the `Drop` trait",
 326             container_ty,
 327         );
 328         err.span_label(move_from_span, "cannot move out of here");
 329         err
 330     }
 331
 332     crate fn cannot_act_on_moved_value(
 333         &self,
 334         use_span: Span,
 335         verb: &str,
 336         optional_adverb_for_moved: &str,
 337         moved_path: Option<String>,
 338     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
 339         let moved_path = moved_path.map(|mp| format!(": `{}`", mp)).unwrap_or_default();
 340
 341         struct_span_err!(
 342             self,
 343             use_span,
 344             E0382,
 345             "{} of {}moved value{}",
 346             verb,
 347             optional_adverb_for_moved,
 348             moved_path,
 349         )
 350     }
 351
 352     crate fn cannot_borrow_path_as_mutable_because(
 353         &self,
 354         span: Span,
 355         path: &str,
 356         reason: &str,
 357     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 358         struct_span_err!(self, span, E0596, "cannot borrow {} as mutable{}", path, reason,)
 359     }
 360
 361     crate fn cannot_mutate_in_immutable_section(
 362         &self,
 363         mutate_span: Span,
 364         immutable_span: Span,
 365         immutable_place: &str,
 366         immutable_section: &str,
 367         action: &str,
 368     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 369         let mut err = struct_span_err!(
 370             self,
 371             mutate_span,
 372             E0510,
 373             "cannot {} {} in {}",
 374             action,
 375             immutable_place,
 376             immutable_section,
 377         );
 378         err.span_label(mutate_span, format!("cannot {}", action));
 379         err.span_label(immutable_span, format!("value is immutable in {}", immutable_section));
 380         err
 381     }
 382
 383     crate fn cannot_borrow_across_generator_yield(
 384         &self,
 385         span: Span,
 386         yield_span: Span,
 387     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 388         let mut err = struct_span_err!(
 389             self,
 390             span,
 391             E0626,
 392             "borrow may still be in use when generator yields",
 393         );
 394         err.span_label(yield_span, "possible yield occurs here");
 395         err
 396     }
 397
 398     crate fn cannot_borrow_across_destructor(
 399         &self,
 400         borrow_span: Span,
 401     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 402         struct_span_err!(
 403             self,
 404             borrow_span,
 405             E0713,
 406             "borrow may still be in use when destructor runs",
 407         )
 408     }
 409
 410     crate fn path_does_not_live_long_enough(
 411         &self,
 412         span: Span,
 413         path: &str,
 414     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 415         struct_span_err!(self, span, E0597, "{} does not live long enough", path,)
 416     }
 417
 418     crate fn cannot_return_reference_to_local(
 419         &self,
 420         span: Span,
 421         return_kind: &str,
 422         reference_desc: &str,
 423         path_desc: &str,
 424     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 425         let mut err = struct_span_err!(
 426             self,
 427             span,
 428             E0515,
 429             "cannot {RETURN} {REFERENCE} {LOCAL}",
 430             RETURN = return_kind,
 431             REFERENCE = reference_desc,
 432             LOCAL = path_desc,
 433         );
 434
 435         err.span_label(
 436             span,
 437             format!("{}s a {} data owned by the current function", return_kind, reference_desc),
 438         );
 439
 440         err
 441     }
 442
 443     crate fn cannot_capture_in_long_lived_closure(
 444         &self,
 445         closure_span: Span,
 446         closure_kind: &str,
 447         borrowed_path: &str,
 448         capture_span: Span,
 449     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 450         let mut err = struct_span_err!(
 451             self,
 452             closure_span,
 453             E0373,
 454             "{} may outlive the current function, \
 455              but it borrows {}, \
 456              which is owned by the current function",
 457             closure_kind,
 458             borrowed_path,
 459         );
 460         err.span_label(capture_span, format!("{} is borrowed here", borrowed_path))
 461             .span_label(closure_span, format!("may outlive borrowed value {}", borrowed_path));
 462         err
 463     }
 464
 465     crate fn thread_local_value_does_not_live_long_enough(
 466         &self,
 467         span: Span,
 468     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 469         struct_span_err!(self, span, E0712, "thread-local variable borrowed past end of function",)
 470     }
 471
 472     crate fn temporary_value_borrowed_for_too_long(
 473         &self,
 474         span: Span,
 475     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
 476         struct_span_err!(self, span, E0716, "temporary value dropped while borrowed",)
 477     }
 478
 479     fn struct_span_err_with_code<S: Into<MultiSpan>>(
 480         &self,
 481         sp: S,
 482         msg: &str,
 483         code: DiagnosticId,
 484     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
 485         self.infcx.tcx.sess.struct_span_err_with_code(sp, msg, code)
 486     }
 487 }
 488
 489 crate fn borrowed_data_escapes_closure<'tcx>(
 490     tcx: TyCtxt<'tcx>,
 491     escape_span: Span,
 492     escapes_from: &str,
 493 ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
 494     struct_span_err!(
 495         tcx.sess,
 496         escape_span,
 497         E0521,
 498         "borrowed data escapes outside of {}",
 499         escapes_from,
 500     )
 501 }