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

   1 // run-pass
   2 // revisions: mirunsafeck thirunsafeck
   3 // [thirunsafeck]compile-flags: -Z thir-unsafeck
   4
   5 #![allow(dead_code)]
   6
   7 use std::mem::needs_drop;
   8 use std::mem::ManuallyDrop;
   9
  10 struct NeedDrop;
  11
  12 impl Drop for NeedDrop {
  13     fn drop(&mut self) {}
  14 }
  15
  16 union UnionOk1<T> {
  17     empty: (),
  18     value: ManuallyDrop<T>,
  19 }
  20
  21 union UnionOk2 {
  22     value: ManuallyDrop<NeedDrop>,
  23 }
  24
  25 #[allow(dead_code)]
  26 union UnionOk3<T: Copy> {
  27     empty: (),
  28     value: T,
  29 }
  30
  31 trait Foo { }
  32
  33 trait ImpliesCopy : Copy { }
  34
  35 #[allow(dead_code)]
  36 union UnionOk4<T: ImpliesCopy> {
  37     value: T,
  38 }
  39
  40 fn main() {
  41     // NeedDrop should not make needs_drop true
  42     assert!(!needs_drop::<UnionOk1<NeedDrop>>());
  43     assert!(!needs_drop::<UnionOk3<&dyn Foo>>());
  44 }