error[E0508]: cannot move out of type `[u8]`, a non-copy slice
  --> $DIR/unsized-exprs2.rs:22:19
   |
LL |     udrop::<[u8]>(foo()[..]);
   |                   ^^^^^^^^^ cannot move out of here

error: aborting due to previous error

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