mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-27 01:04:03 +00:00
cc80106cb5
When encountering multiple mutable borrows, suggest cloning and adding
derive annotations as needed.
```
error[E0596]: cannot borrow `sm.x` as mutable, as it is behind a `&` reference
--> $DIR/accidentally-cloning-ref-borrow-error.rs:32:9
|
LL | foo(&mut sm.x);
| ^^^^^^^^^ `sm` is a `&` reference, so the data it refers to cannot be borrowed as mutable
|
help: `Str` doesn't implement `Clone`, so this call clones the reference `&Str`
--> $DIR/accidentally-cloning-ref-borrow-error.rs:31:21
|
LL | let mut sm = sr.clone();
| ^^^^^^^
help: consider annotating `Str` with `#[derive(Clone)]`
|
LL + #[derive(Clone)]
LL | struct Str {
|
help: consider specifying this binding's type
|
LL | let mut sm: &mut Str = sr.clone();
| ++++++++++
```
```
error[E0596]: cannot borrow `*inner` as mutable, as it is behind a `&` reference
--> $DIR/issue-91206.rs:14:5
|
LL | inner.clear();
| ^^^^^ `inner` is a `&` reference, so the data it refers to cannot be borrowed as mutable
|
help: you can `clone` the `Vec<usize>` value and consume it, but this might not be your desired behavior
--> $DIR/issue-91206.rs:11:17
|
LL | let inner = client.get_inner_ref();
| ^^^^^^^^^^^^^^^^^^^^^^
help: consider specifying this binding's type
|
LL | let inner: &mut Vec<usize> = client.get_inner_ref();
| +++++++++++++++++
```
39 lines
714 B
Rust
39 lines
714 B
Rust
#[derive(Debug)]
|
|
struct X<T>(T);
|
|
|
|
impl<T: Clone> Clone for X<T> {
|
|
fn clone(&self) -> X<T> {
|
|
X(self.0.clone())
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
struct Y;
|
|
|
|
#[derive(Debug)]
|
|
struct Str {
|
|
x: Option<i32>,
|
|
}
|
|
|
|
fn foo(s: &mut Option<i32>) {
|
|
if s.is_none() {
|
|
*s = Some(0);
|
|
}
|
|
println!("{:?}", s);
|
|
}
|
|
|
|
fn bar<T: std::fmt::Debug>(s: &mut X<T>) {
|
|
println!("{:?}", s);
|
|
}
|
|
fn main() {
|
|
let s = Str { x: None };
|
|
let sr = &s;
|
|
let mut sm = sr.clone();
|
|
foo(&mut sm.x); //~ ERROR cannot borrow `sm.x` as mutable, as it is behind a `&` reference
|
|
|
|
let x = X(Y);
|
|
let xr = &x;
|
|
let mut xm = xr.clone();
|
|
bar(&mut xm); //~ ERROR cannot borrow data in a `&` reference as mutable
|
|
}
|