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 } => {},
| ++++++++
```
24 lines
801 B
Rust
24 lines
801 B
Rust
// Issue 27282: Example 1: This sidesteps the AST checks disallowing
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// mutable borrows in match guards by hiding the mutable borrow in a
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// guard behind a move (of the ref mut pattern id) within a closure.
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//@ run-rustfix
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#![feature(if_let_guard)]
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fn main() {
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match Some(&4) {
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None => {},
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ref mut foo
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if { (|| { let mut bar = foo.clone(); bar.take() })(); false } => {},
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//~^ ERROR cannot move out of `foo` in pattern guard [E0507]
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Some(s) => std::process::exit(*s),
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}
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match Some(&4) {
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None => {},
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ref mut foo
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if let Some(()) = { (|| { let mut bar = foo.clone(); bar.take() })(); None } => {},
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//~^ ERROR cannot move out of `foo` in pattern guard [E0507]
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Some(s) => std::process::exit(*s),
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}
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}
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