/// behavior when `ptr` is used inside the `unsafe` block:
///
/// ```no_run
+ /// # #![allow(unused_must_use)]
/// use std::ffi::{CString};
///
/// let ptr = CString::new("Hello").unwrap().as_ptr();
/// To fix the problem, bind the `CString` to a local variable:
///
/// ```no_run
+ /// # #![allow(unused_must_use)]
/// use std::ffi::{CString};
///
/// let hello = CString::new("Hello").unwrap();