Suggest making binding mut on &mut reborrow

[estebank]

When a binding needs to be mutably reborrowed multiple times, suggesting removing &mut will lead to follow up errors. Instead suggest both making the binding mutable and removing the reborrow.

error[E0596]: cannot borrow `outer` as mutable, as it is not declared as mutable --> f14.rs:2:12 | 2 | match (&mut outer, 23) { | ^^^^^^^^^^ cannot borrow as mutable | note: the binding is already a mutable borrow --> f14.rs:1:16 | 1 | fn test(outer: &mut Option<i32>) { | ^^^^^^^^^^^^^^^^ help: consider making the binding mutable if you need to reborrow multiple times | 1 | fn test(mut outer: &mut Option<i32>) { | +++ help: if there is only one mutable reborrow, remove the `&mut` | 2 - match (&mut outer, 23) { 2 + match (outer, 23) { | 

Address #81059.

[rustbot]

r? @BoxyUwU

rustbot has assigned @BoxyUwU.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[bors]

☔ The latest upstream changes (presumably #142390) made this pull request unmergeable. Please resolve the merge conflicts.