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

   1 //! ALL valid bit patterns of the source must be valid bit patterns of the
   2 //! destination type, unless validity is assumed.
   3
   4 #![crate_type = "lib"]
   5 #![feature(transmutability)]
   6 #![allow(dead_code, incomplete_features, non_camel_case_types)]
   7
   8 mod assert {
   9     use std::mem::BikeshedIntrinsicFrom;
  10     pub struct Context;
  11
  12     pub fn is_transmutable<Src, Dst>()
  13     where
  14         Dst: BikeshedIntrinsicFrom<Src, Context, false, false, false, true>
  15         // validity is NOT assumed ----------------------------^^^^^
  16     {}
  17 }
  18
  19 #[derive(Clone, Copy)] #[repr(u8)] enum Ox00 { V = 0x00 }
  20 #[derive(Clone, Copy)] #[repr(u8)] enum Ox7F { V = 0x7F }
  21 #[derive(Clone, Copy)] #[repr(u8)] enum OxFF { V = 0xFF }
  22
  23 fn test() {
  24     #[repr(C)]
  25     union A {
  26         a: Ox00,
  27         b: Ox7F,
  28     }
  29
  30     #[repr(C)]
  31     union B {
  32         a: Ox7F,
  33         b: OxFF,
  34     }
  35
  36     assert::is_transmutable::<A, B>(); //~ ERROR cannot be safely transmuted
  37     assert::is_transmutable::<B, A>(); //~ ERROR cannot be safely transmuted
  38 }