Incorrect suggestion when trying to write to an immutable field in an async function #93093
Description
Given the following code: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=df6e36b97b73bd3e3ea0fdfe9325b1c9
struct S { foo: usize }
impl S {
async fn bar(&self) {
self.foo += 1;
}
}The current output is:
error[E0594]: cannot assign to `self.foo`, which is behind a `&` reference
--> src/lib.rs:4:9
|
3 | async fn bar(&self) {
| ----- help: consider changing this to be a mutable reference: `&mut S`
4 | self.foo += 1;
| ^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
Ideally the output should look like:
error[E0594]: cannot assign to `self.foo`, which is behind a `&` reference
--> src/lib.rs:4:9
|
3 | async fn bar(&self) {
| ----- help: consider changing this to be a mutable reference: `&mut self`
4 | self.foo += 1;
| ^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
&mut S is not a valid argument; it needs to be either &mut self or some_name: &mut S. For some reason this problem only happens when the function is async.