src/test/ui/cell-does-not-clone.rs

   1 // run-pass
   2
   3 #![allow(dead_code)]
   4
   5 use std::cell::Cell;
   6
   7 #[derive(Copy)]
   8 struct Foo {
   9     x: isize
  10 }
  11
  12 impl Clone for Foo {
  13     fn clone(&self) -> Foo {
  14         // Using Cell in any way should never cause clone() to be
  15         // invoked -- after all, that would permit evil user code to
  16         // abuse `Cell` and trigger crashes.
  17
  18         panic!();
  19     }
  20 }
  21
  22 pub fn main() {
  23     let x = Cell::new(Foo { x: 22 });
  24     let _y = x.get();
  25     let _z = x.clone();
  26 }