// Some optimizations remove ZST accesses, thus masking this UB. //@compile-flags: -Zmir-opt-level=0 fn main() { // Not using the () type here, as writes of that type do not even have MIR generated. // Also not assigning directly as that's array initialization, not assignment. let zst_val = [1u8; 0]; // make sure ZST accesses are checked against being "truly" dangling pointers // (that are out-of-bounds). let mut x_box = Box::new(1u8); let x = (&mut *x_box as *mut u8).wrapping_offset(1); // This one is just "at the edge", but still okay unsafe { *(x as *mut [u8; 0]) = zst_val }; // One byte further is OOB. let x = x.wrapping_offset(1); unsafe { *(x as *mut [u8; 0]) = zst_val }; //~ ERROR: out-of-bounds }