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Suggest ref mut for pattern matching assignment

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This commit is contained in:
yukang 2024-01-06 13:13:18 +08:00
parent 7bb4f0889e
commit be9dbe9102
8 changed files with 164 additions and 41 deletions
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17
compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
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@ -3706,7 +3706,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
| None => (self.describe_any_place(place.as_ref()), assigned_span),
Some(decl) => (self.describe_any_place(err_place.as_ref()), decl.source_info.span),
};
let mut err = self.cannot_reassign_immutable(span, &place_description, from_arg);
let msg = if from_arg {
"cannot assign to immutable argument"
@ -3726,6 +3725,22 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
format!("mut {name}"),
Applicability::MachineApplicable,
);
if !from_arg
&& matches!(
decl.local_info(),
LocalInfo::User(BindingForm::Var(VarBindingForm {
opt_match_place: Some((Some(_), _)),
..
}))
)
{
err.span_suggestion(
decl.source_info.span,
"to modify the original value, take a borrow instead",
format!("ref mut {name}"),
Applicability::MaybeIncorrect,
);
}
}
err.span_label(span, msg);
self.buffer_error(err);