warning[E0507]: cannot move out of borrowed content
  --> $DIR/borrowck-migrate-to-nll.rs:25:17
   |
LL |                 (|| { let bar = foo; bar.take() })();
   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot move out of borrowed content
   |
   = warning: this error has been downgraded to a warning for backwards compatibility with previous releases
   = warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future
   = note: for more information, try `rustc --explain E0729`