// 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 // (into deallocated allocations). let mut x_box = Box::new(1u8); let x = &mut *x_box as *mut _ as *mut [u8; 0]; drop(x_box); unsafe { *x = zst_val; } //~ ERROR dereferenced after this allocation got freed }