src/test/ui/consts/const-eval/ub-uninhabit.rs

   1 // stderr-per-bitwidth
   2 #![allow(const_err)] // make sure we cannot allow away the errors tested here
   3
   4 use std::mem;
   5
   6 #[derive(Copy, Clone)]
   7 enum Bar {}
   8
   9 #[repr(C)]
  10 union MaybeUninit<T: Copy> {
  11     uninit: (),
  12     init: T,
  13 }
  14
  15 const BAD_BAD_BAD: Bar = unsafe { MaybeUninit { uninit: () }.init };
  16 //~^ ERROR it is undefined behavior to use this value
  17
  18 const BAD_BAD_REF: &Bar = unsafe { mem::transmute(1usize) };
  19 //~^ ERROR it is undefined behavior to use this value
  20
  21 const BAD_BAD_ARRAY: [Bar; 1] = unsafe { MaybeUninit { uninit: () }.init };
  22 //~^ ERROR it is undefined behavior to use this value
  23
  24 fn main() {}