error[E0506]: cannot assign to `self.container_field` because it is borrowed
  --> $DIR/issue-81365-9.rs:21:9
   |
LL |         let first = &Deref::deref(self).target_field;
   |                                   ---- `self.container_field` is borrowed here
LL |         self.container_field = true;
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `self.container_field` is assigned to here but it was already borrowed
LL |         first;
   |         ----- borrow later used here

error: aborting due to previous error

For more information about this error, try `rustc --explain E0506`.