| // run-pass | |
| #![feature(unboxed_closures)] | |
| #![feature(fn_traits)] | |
| struct Fun<F>(F); | |
| impl<F, T> FnOnce<(T,)> for Fun<F> where F: Fn(T) -> T { | |
| type Output = T; | |
| extern "rust-call" fn call_once(self, (t,): (T,)) -> T { | |
| (self.0)(t) | |
| } | |
| } | |
| fn main() { | |
| let fun = Fun(|i: isize| i * 2); | |
| println!("{}", fun(3)); | |
| } |