bjoernager/rust
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Tweak .clone() suggestion to work in more cases

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When going through auto-deref, the `<T as Clone>` impl sometimes needs
to be specified for rustc to actually clone the value and not the
reference.

```
error[E0507]: cannot move out of dereference of `S`
  --> $DIR/needs-clone-through-deref.rs:15:18
   |
LL |         for _ in self.clone().into_iter() {}
   |                  ^^^^^^^^^^^^ ----------- value moved due to this method call
   |                  |
   |                  move occurs because value has type `Vec<usize>`, which does not implement the `Copy` trait
   |
note: `into_iter` takes ownership of the receiver `self`, which moves value
  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
help: you can `clone` the value and consume it, but this might not be your desired behavior
   |
LL |         for _ in <Vec<usize> as Clone>::clone(&self.clone()).into_iter() {}
   |                  ++++++++++++++++++++++++++++++            +
```

CC #109429.
This commit is contained in:
Esteban Küber 2023-11-19 23:53:31 +00:00
parent 0e2dac8375
commit 03c88aaf21
12 changed files with 86 additions and 18 deletions
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20
compiler/rustc_borrowck/src/diagnostics/mod.rs
View file

@ -1135,11 +1135,25 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
)
&& self.infcx.predicate_must_hold_modulo_regions(&o)
{
err.span_suggestion_verbose(
move_span.shrink_to_hi(),
let sugg = if moved_place
.iter_projections()
.any(|(_, elem)| matches!(elem, ProjectionElem::Deref))
{
vec![
// We use the fully-qualified path because `.clone()` can
// sometimes choose `<&T as Clone>` instead of `<T as Clone>`
// when going through auto-deref, so this ensures that doesn't
// happen, causing suggestions for `.clone().clone()`.
(move_span.shrink_to_lo(), format!("<{ty} as Clone>::clone(&")),
(move_span.shrink_to_hi(), ")".to_string()),
]
} else {
vec![(move_span.shrink_to_hi(), ".clone()".to_string())]
};
err.multipart_suggestion_verbose(
"you can `clone` the value and consume it, but this might not be \
your desired behavior",
".clone()".to_string(),
sugg,
Applicability::MaybeIncorrect,
);
}