src/test/ui/unsafe/ranged_ints4_const.rs

   1 // revisions: mirunsafeck thirunsafeck
   2 // [thirunsafeck]compile-flags: -Z thir-unsafeck
   3
   4 #![feature(rustc_attrs)]
   5
   6 #[rustc_layout_scalar_valid_range_start(1)]
   7 #[repr(transparent)]
   8 pub(crate) struct NonZero<T>(pub(crate) T);
   9 fn main() {}
  10
  11 const fn foo() -> NonZero<u32> {
  12     let mut x = unsafe { NonZero(1) };
  13     x.0 = 0;
  14     //~^ ERROR mutation of layout constrained field is unsafe
  15     x
  16 }
  17
  18 const fn bar() -> NonZero<u32> {
  19     let mut x = unsafe { NonZero(1) };
  20     unsafe { x.0 = 0 }; // this is UB
  21     x
  22 }