//@ run-pass fn ho(f: F) -> isize where F: FnOnce(isize) -> isize { let n: isize = f(3); return n; } fn direct(x: isize) -> isize { return x + 1; } pub fn main() { let a: isize = direct(3); // direct let b: isize = ho(direct); // indirect unbound assert_eq!(a, b); }