error[E0596]: cannot borrow `b` as mutable, as it is not declared as mutable
  --> $DIR/mut-borrow-of-mut-ref.rs:5:7
   |
LL |     g(&mut b);
   |       ^^^^^^
   |       |
   |       cannot borrow as mutable
   |       try removing `&mut` here

error[E0596]: cannot borrow `b` as mutable, as it is not declared as mutable
  --> $DIR/mut-borrow-of-mut-ref.rs:7:12
   |
LL |     g(&mut &mut b);
   |            ^^^^^^
   |            |
   |            cannot borrow as mutable
   |            try removing `&mut` here

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0596`.