#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::ffi::CStr;
use std::os::raw::c_char;
unsafe extern "C" fn my_string() -> *const c_char {
    c"hello".as_ptr()
}
fn main() {
    unsafe {
        let slice = CStr::from_ptr(my_string());
        println!(
            "string buffer size without nul terminator: {}", slice.to_bytes().len()
        );
    }
}