14473adf42
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.
25 lines
762 B
Rust
25 lines
762 B
Rust
fn main() {
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let foos = vec![String::new()];
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let bars = vec![""];
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let mut baz = vec![];
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let mut qux = vec![];
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for foo in foos {
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//~^ NOTE this reinitialization might get skipped
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//~| NOTE move occurs because `foo` has type `String`
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for bar in &bars {
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//~^ NOTE inside of this loop
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//~| HELP consider moving the expression out of the loop
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//~| NOTE in this expansion of desugaring of `for` loop
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if foo == *bar {
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baz.push(foo);
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//~^ NOTE value moved here
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//~| HELP consider cloning the value
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continue;
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}
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}
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qux.push(foo);
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//~^ ERROR use of moved value
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//~| NOTE value used here
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}
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}
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