error[E0499]: cannot borrow `*x.__pointer` as mutable more than once at a time
  --> $DIR/pin-reborrow-once.rs:12:14
   |
LL |     twice(x, x);
   |     ----- -  ^ second mutable borrow occurs here
   |     |     |
   |     |     first mutable borrow occurs here
   |     first borrow later used by call

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0499`.