2d3435b4df
When encountering a lifetime error on a type that *holds* a type that
doesn't implement `Clone`, explore the item's body for potential calls
to `.clone()` that are only cloning the reference `&T` instead of `T`
because `T: !Clone`. If we find this, suggest `T: Clone`.
```
error[E0502]: cannot borrow `*list` as mutable because it is also borrowed as immutable
--> $DIR/clone-on-ref.rs:7:5
|
LL | for v in list.iter() {
| ---- immutable borrow occurs here
LL | cloned_items.push(v.clone())
| ------- this call doesn't do anything, the result is still `&T` because `T` doesn't implement `Clone`
LL | }
LL | list.push(T::default());
| ^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL |
LL | drop(cloned_items);
| ------------ immutable borrow later used here
|
help: consider further restricting this bound
|
LL | fn foo<T: Default + Clone>(list: &mut Vec<T>) {
| +++++++
```
```
error[E0505]: cannot move out of `x` because it is borrowed
--> $DIR/clone-on-ref.rs:23:10
|
LL | fn qux(x: A) {
| - binding `x` declared here
LL | let a = &x;
| -- borrow of `x` occurs here
LL | let b = a.clone();
| ------- this call doesn't do anything, the result is still `&A` because `A` doesn't implement `Clone`
LL | drop(x);
| ^ move out of `x` occurs here
LL |
LL | println!("{b:?}");
| ----- borrow later used here
|
help: consider annotating `A` with `#[derive(Clone)]`
|
LL + #[derive(Clone)]
LL | struct A;
|
```
65 lines
2.2 KiB
Plaintext
65 lines
2.2 KiB
Plaintext
error[E0502]: cannot borrow `*list` as mutable because it is also borrowed as immutable
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--> $DIR/clone-on-ref.rs:7:5
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LL | for v in list.iter() {
|
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| ---- immutable borrow occurs here
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LL | cloned_items.push(v.clone())
|
|
| ------- this call doesn't do anything, the result is still `&T` because `T` doesn't implement `Clone`
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LL | }
|
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LL | list.push(T::default());
|
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| ^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
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LL |
|
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LL | drop(cloned_items);
|
|
| ------------ immutable borrow later used here
|
|
|
|
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help: consider further restricting this bound
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LL | fn foo<T: Default + Clone>(list: &mut Vec<T>) {
|
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| +++++++
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error[E0505]: cannot move out of `x` because it is borrowed
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--> $DIR/clone-on-ref.rs:14:10
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LL | fn bar<T: std::fmt::Display>(x: T) {
|
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| - binding `x` declared here
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LL | let a = &x;
|
|
| -- borrow of `x` occurs here
|
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LL | let b = a.clone();
|
|
| ------- this call doesn't do anything, the result is still `&T` because `T` doesn't implement `Clone`
|
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LL | drop(x);
|
|
| ^ move out of `x` occurs here
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LL |
|
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LL | println!("{b}");
|
|
| --- borrow later used here
|
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help: consider further restricting this bound
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LL | fn bar<T: std::fmt::Display + Clone>(x: T) {
|
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| +++++++
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error[E0505]: cannot move out of `x` because it is borrowed
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--> $DIR/clone-on-ref.rs:23:10
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LL | fn qux(x: A) {
|
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| - binding `x` declared here
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LL | let a = &x;
|
|
| -- borrow of `x` occurs here
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LL | let b = a.clone();
|
|
| ------- this call doesn't do anything, the result is still `&A` because `A` doesn't implement `Clone`
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LL | drop(x);
|
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| ^ move out of `x` occurs here
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LL |
|
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LL | println!("{b:?}");
|
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| ----- borrow later used here
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help: consider annotating `A` with `#[derive(Clone)]`
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LL + #[derive(Clone)]
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LL | struct A;
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error: aborting due to 3 previous errors
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Some errors have detailed explanations: E0502, E0505.
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For more information about an error, try `rustc --explain E0502`.
|