src/test/ui/issues/issue-20544.rs

   1 // run-pass
   2 #![feature(unboxed_closures)]
   3 #![feature(fn_traits)]
   4
   5 struct Fun<F>(F);
   6
   7 impl<F, T> FnOnce<(T,)> for Fun<F> where F: Fn(T) -> T {
   8     type Output = T;
   9
  10     extern "rust-call" fn call_once(self, (t,): (T,)) -> T {
  11         (self.0)(t)
  12     }
  13 }
  14
  15 fn main() {
  16     let fun = Fun(|i: isize| i * 2);
  17     println!("{}", fun(3));
  18 }