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4aba2c55e6
Start pointing to where bindings were declared when they are captured in closures:
```
error[E0597]: `x` does not live long enough
--> $DIR/suggest-return-closure.rs:23:9
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LL | let x = String::new();
| - binding `x` declared here
...
LL | |c| {
| --- value captured here
LL | x.push(c);
| ^ borrowed value does not live long enough
...
LL | }
| -- borrow later used here
| |
| `x` dropped here while still borrowed
```
Suggest cloning in more cases involving closures:
```
error[E0507]: cannot move out of `foo` in pattern guard
--> $DIR/issue-27282-move-ref-mut-into-guard.rs:11:19
|
LL | if { (|| { let mut bar = foo; bar.take() })(); false } => {},
| ^^ --- move occurs because `foo` has type `&mut Option<&i32>`, which does not implement the `Copy` trait
| |
| `foo` is moved here
|
= note: variables bound in patterns cannot be moved from until after the end of the pattern guard
help: consider cloning the value if the performance cost is acceptable
|
LL | if { (|| { let mut bar = foo.clone(); bar.take() })(); false } => {},
| ++++++++
```
66 lines
2.6 KiB
Plaintext
66 lines
2.6 KiB
Plaintext
error[E0597]: `factorial` does not live long enough
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--> $DIR/unboxed-closures-failed-recursive-fn-1.rs:15:17
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LL | let mut factorial: Option<Box<dyn Fn(u32) -> u32>> = None;
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| ------------- binding `factorial` declared here
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LL |
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LL | let f = |x: u32| -> u32 {
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| --------------- value captured here
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LL | let g = factorial.as_ref().unwrap();
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| ^^^^^^^^^ borrowed value does not live long enough
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...
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LL | }
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| -
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| `factorial` dropped here while still borrowed
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| borrow might be used here, when `factorial` is dropped and runs the destructor for type `Option<Box<dyn Fn(u32) -> u32>>`
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error[E0506]: cannot assign to `factorial` because it is borrowed
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--> $DIR/unboxed-closures-failed-recursive-fn-1.rs:20:5
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LL | let f = |x: u32| -> u32 {
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| --------------- `factorial` is borrowed here
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LL | let g = factorial.as_ref().unwrap();
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| --------- borrow occurs due to use in closure
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...
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LL | factorial = Some(Box::new(f));
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| ^^^^^^^^^
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| `factorial` is assigned to here but it was already borrowed
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| borrow later used here
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error[E0597]: `factorial` does not live long enough
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--> $DIR/unboxed-closures-failed-recursive-fn-1.rs:28:17
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LL | let mut factorial: Option<Box<dyn Fn(u32) -> u32 + 'static>> = None;
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| ------------- ----------------------------------------- type annotation requires that `factorial` is borrowed for `'static`
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| binding `factorial` declared here
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LL |
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LL | let f = |x: u32| -> u32 {
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| --------------- value captured here
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LL | let g = factorial.as_ref().unwrap();
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| ^^^^^^^^^ borrowed value does not live long enough
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...
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LL | }
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| - `factorial` dropped here while still borrowed
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error[E0506]: cannot assign to `factorial` because it is borrowed
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--> $DIR/unboxed-closures-failed-recursive-fn-1.rs:33:5
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LL | let mut factorial: Option<Box<dyn Fn(u32) -> u32 + 'static>> = None;
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| ----------------------------------------- type annotation requires that `factorial` is borrowed for `'static`
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LL |
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LL | let f = |x: u32| -> u32 {
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| --------------- `factorial` is borrowed here
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LL | let g = factorial.as_ref().unwrap();
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| --------- borrow occurs due to use in closure
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...
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LL | factorial = Some(Box::new(f));
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| ^^^^^^^^^ `factorial` is assigned to here but it was already borrowed
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error: aborting due to 4 previous errors
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Some errors have detailed explanations: E0506, E0597.
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For more information about an error, try `rustc --explain E0506`.
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