// run-pass fn example_err(prog: &str, arg: &str) { println!("{}: {}", prog, arg) } fn exit<F>(print: F, prog: &str, arg: &str) where F: FnOnce(&str, &str) { print(prog, arg); } struct X<F> where F: FnOnce(&str, &str) { err: F, } impl<F> X<F> where F: FnOnce(&str, &str) { pub fn boom(self) { exit(self.err, "prog", "arg"); } } pub fn main(){ let val = X { err: example_err, }; val.boom(); }