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
|
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
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LL | if { (|| { let mut bar = foo.clone(); bar.take() })(); false } => {},
| ++++++++
```
42 lines
1.5 KiB
Rust
42 lines
1.5 KiB
Rust
fn fn_once() -> _ {
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//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types [E0121]
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//~| NOTE not allowed in type signatures
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//~| HELP replace with an appropriate return type
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//~| SUGGESTION impl FnOnce()
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//~| NOTE for more information on `Fn` traits and closure types
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let x = String::new();
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|| {
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drop(x);
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}
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}
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fn fn_mut() -> _ {
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//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types [E0121]
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//~| NOTE not allowed in type signatures
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//~| HELP replace with an appropriate return type
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//~| SUGGESTION impl FnMut(char)
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//~| NOTE for more information on `Fn` traits and closure types
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let x = String::new();
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//~^ HELP: consider changing this to be mutable
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//~| NOTE binding `x` declared here
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|c| { //~ NOTE: value captured here
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x.push(c);
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//~^ ERROR: does not live long enough
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//~| NOTE: does not live long enough
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//~| NOTE: cannot borrow as mutable
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//~| ERROR: not declared as mutable
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}
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} //~ NOTE: borrow later used here
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//~^ NOTE: dropped here
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fn fun() -> _ {
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//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types [E0121]
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//~| NOTE not allowed in type signatures
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//~| HELP replace with an appropriate return type
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//~| SUGGESTION impl Fn() -> i32
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//~| NOTE for more information on `Fn` traits and closure types
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|| 1i32
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}
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fn main() {}
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