src/test/ui/transmutability/unions/should_permit_intersecting_if_validity_is_assumed.rs

   1 // check-pass
   2 //! If validity is assumed, there need only be one matching bit-pattern between
   3 //! the source and destination types.
   4
   5 #![crate_type = "lib"]
   6 #![feature(transmutability)]
   7 #![allow(dead_code, incomplete_features, non_camel_case_types)]
   8
   9 mod assert {
  10     use std::mem::BikeshedIntrinsicFrom;
  11     pub struct Context;
  12
  13     pub fn is_maybe_transmutable<Src, Dst>()
  14     where
  15         Dst: BikeshedIntrinsicFrom<Src, Context, false, false, true, true>
  16         // validity IS assumed --------------------------------^^^^
  17     {}
  18 }
  19
  20 #[derive(Clone, Copy)] #[repr(u8)] enum Ox00 { V = 0x00 }
  21 #[derive(Clone, Copy)] #[repr(u8)] enum Ox7F { V = 0x7F }
  22 #[derive(Clone, Copy)] #[repr(u8)] enum OxFF { V = 0xFF }
  23
  24 fn test() {
  25     #[repr(C)]
  26     union A {
  27         a: Ox00,
  28         b: Ox7F,
  29     }
  30
  31     #[repr(C)]
  32     union B {
  33         a: Ox7F,
  34         b: OxFF,
  35     }
  36
  37     assert::is_maybe_transmutable::<A, B>();
  38     assert::is_maybe_transmutable::<B, A>();
  39 }