src/test/ui/union/union-manuallydrop-rpass.rs

   1 #![allow(dead_code)]
   2 // run-pass
   3
   4 use std::mem::needs_drop;
   5 use std::mem::ManuallyDrop;
   6
   7 struct NeedDrop;
   8
   9 impl Drop for NeedDrop {
  10     fn drop(&mut self) {}
  11 }
  12
  13 union UnionOk1<T> {
  14     empty: (),
  15     value: ManuallyDrop<T>,
  16 }
  17
  18 union UnionOk2 {
  19     value: ManuallyDrop<NeedDrop>,
  20 }
  21
  22 #[allow(dead_code)]
  23 union UnionOk3<T: Copy> {
  24     empty: (),
  25     value: T,
  26 }
  27
  28 trait Foo { }
  29
  30 trait ImpliesCopy : Copy { }
  31
  32 #[allow(dead_code)]
  33 union UnionOk4<T: ImpliesCopy> {
  34     value: T,
  35 }
  36
  37 fn main() {
  38     // NeedDrop should not make needs_drop true
  39     assert!(!needs_drop::<UnionOk1<NeedDrop>>());
  40     assert!(!needs_drop::<UnionOk3<&dyn Foo>>());
  41 }