Suggest removing `&mut x` when `x: &mut T` and `&mut T` is expected type

[Centril]

An example:

struct A;

fn bar(x: &mut A) {}

fn foo(x: &mut A) {
    bar(&mut x);
}

results in:

error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 --> src/lib.rs:6:9
  |
5 | fn foo(x: &mut A) {
  |        - help: consider changing this to be mutable: `mut x`
6 |     bar(&mut x);
  |         ^^^^^^ cannot borrow as mutable

but we could say:

error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 --> src/lib.rs:6:9
  |
5 | fn foo(x: &mut A) {
6 |     bar(&mut x);
  |         ^^^^^^ cannot borrow as mutable
  |         ---- help: remove the unnecessary `&mut` here

[LeSeulArtichaut]

I’d be interested in working on this. I’ll probably take a look in the next few days.

[LeSeulArtichaut]

@rustbot claim

[LeSeulArtichaut]

Looks like this is a regression, see 3303e68

[LeSeulArtichaut]

@rustbot release-assignment

[ibraheemdev]

I think this issue was fixed:

error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 --> src/lib.rs:6:9
  |
6 |     bar(&mut x);
  |         ^^^^^^
  |         |
  |         cannot borrow as mutable
  |         try removing `&mut` here

[ibraheemdev]

Actually, that should be a help message. @rustbot claim