#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::ffi::CStr;
use std::os::raw::c_char;
fn work(data: &CStr) {
    unsafe extern "C" fn work_with(s: *const c_char) {}
    unsafe { work_with(data.as_ptr()) }
}
fn main() {
    let s = c"Hello world!";
    work(&s);
}