Detect method not found on arbitrary self type with different mutability ``` error[E0599]: no method named `x` found for struct `Pin<&S>` in the current scope --> $DIR/arbitrary_self_type_mut_difference.rs:11:18 | LL | Pin::new(&S).x(); | ^ help: there is a method with a similar name: `y` | note: method is available for `Pin<&mut S>` --> $DIR/arbitrary_self_type_mut_difference.rs:6:5 | LL | fn x(self: Pin<&mut Self>) {} | ^^^^^^^^^^^^^^^^^^^^^^^^^^ ``` Related to #57994, as one of the presented cases can lead to code like this.