src/test/ui/unboxed-closures/unboxed-closures-fnmut-as-fnonce.rs

   1 // run-pass
   2 // Checks that the Fn trait hierarchy rules permit
   3 // FnMut or FnOnce to be used where FnMut is implemented.
   4
   5 #![feature(unboxed_closures, fn_traits)]
   6
   7 struct S;
   8
   9 impl FnMut<(i32,)> for S {
  10     extern "rust-call" fn call_mut(&mut self, (x,): (i32,)) -> i32 {
  11         x * x
  12     }
  13 }
  14
  15 impl FnOnce<(i32,)> for S {
  16     type Output = i32;
  17
  18     extern "rust-call" fn call_once(mut self, args: (i32,)) -> i32 { self.call_mut(args) }
  19 }
  20
  21 fn call_it_mut<F:FnMut(i32)->i32>(f: &mut F, x: i32) -> i32 {
  22     f(x)
  23 }
  24
  25 fn call_it_once<F:FnOnce(i32)->i32>(f: F, x: i32) -> i32 {
  26     f(x)
  27 }
  28
  29 fn main() {
  30     let y = call_it_mut(&mut S, 22);
  31     let z = call_it_once(S, 22);
  32     assert_eq!(y, z);
  33 }