rust/tests/compile-fail/undefined_byte_read.rs

// This should fail even without validation
// compile-flags: -Zmir-emit-validate=0

fn main() {
    let v: Vec<u8> = Vec::with_capacity(10);
    let undef = unsafe { *v.get_unchecked(5) };
    let x = undef + 1; //~ ERROR: error
    //~^ NOTE attempted to read undefined bytes
    panic!("this should never print: {}", x);
}