error[E0508]: cannot move out of type `[u8]`, a non-copy slice
  --> $DIR/unsized-exprs2.rs:22:5
   |
LL |     udrop::<[u8]>(foo()[..]);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^
   |     |
   |     cannot move out of here
   |     move occurs because value has type `[u8]`, which does not implement the `Copy` trait

error: aborting due to previous error

For more information about this error, try `rustc --explain E0508`.