error[E0525]: expected a closure that implements the `Fn` trait, but this closure only implements `FnOnce`
  --> $DIR/unboxed-closures-infer-fn-once-move-from-projection.rs:14:13
   |
LL |     let c = || drop(y.0);
   |             ^^      --- closure is `FnOnce` because it moves the variable `y` out of its environment
   |             |
   |             this closure implements `FnOnce`, not `Fn`
LL |     foo(c);
   |     --- the requirement to implement `Fn` derives from here

error: aborting due to previous error

For more information about this error, try `rustc --explain E0525`.