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When encountering a move error on a value within a loop of any kind,
identify if the moved value belongs to a call expression that should not
be cloned and avoid the semantically incorrect suggestion. Also try to
suggest moving the call expression outside of the loop instead.
```
error[E0382]: use of moved value: `vec`
--> $DIR/recreating-value-in-loop-condition.rs:6:33
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LL | let vec = vec!["one", "two", "three"];
| --- move occurs because `vec` has type `Vec<&str>`, which does not implement the `Copy` trait
LL | while let Some(item) = iter(vec).next() {
| ----------------------------^^^--------
| | |
| | value moved here, in previous iteration of loop
| inside of this loop
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note: consider changing this parameter type in function `iter` to borrow instead if owning the value isn't necessary
--> $DIR/recreating-value-in-loop-condition.rs:1:17
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LL | fn iter<T>(vec: Vec<T>) -> impl Iterator<Item = T> {
| ---- ^^^^^^ this parameter takes ownership of the value
| |
| in this function
help: consider moving the expression out of the loop so it is only moved once
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LL ~ let mut value = iter(vec);
LL ~ while let Some(item) = value.next() {
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```
We use the presence of a `break` in the loop that would be affected by
the moved value as a heuristic for "shouldn't be cloned".
Fix #121466.
32 lines
1.2 KiB
Plaintext
32 lines
1.2 KiB
Plaintext
error[E0382]: use of moved value: `value`
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--> $DIR/mut-borrow-in-loop-2.rs:30:23
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LL | fn this_does_not<'a, R>(value: &'a mut Events<R>) {
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| ----- move occurs because `value` has type `&mut Events<R>`, which does not implement the `Copy` trait
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LL | for _ in 0..3 {
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| ------------- inside of this loop
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LL | Other::handle(value);
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| ^^^^^ value moved here, in previous iteration of loop
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note: consider changing this parameter type in function `handle` to borrow instead if owning the value isn't necessary
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--> $DIR/mut-borrow-in-loop-2.rs:8:22
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LL | fn handle(value: T) -> Self;
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| ------ ^ this parameter takes ownership of the value
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| |
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| in this function
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help: consider moving the expression out of the loop so it is only moved once
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LL ~ let mut value = Other::handle(value);
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LL ~ for _ in 0..3 {
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LL ~ value;
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help: consider creating a fresh reborrow of `value` here
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LL | Other::handle(&mut *value);
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| ++++++
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error: aborting due to 1 previous error
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For more information about this error, try `rustc --explain E0382`.
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