error[E0502]: cannot borrow `this.x` as mutable because it is also borrowed as immutable
  --> $DIR/borrowck-closures-unique-imm.rs:11:9
   |
LL |         let p = &this.x;
   |                 ------- immutable borrow occurs here
LL |         &mut this.x;
   |         ^^^^^^^^^^^ mutable borrow occurs here
LL |         p.use_ref();
   |         ----------- immutable borrow later used here

error: aborting due to previous error

For more information about this error, try `rustc --explain E0502`.