compiler/rustc_borrowck/src/borrowck_errors.rs

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