Add `try_cmp` function to `X509NameRef`s

use cfg_if::cfg_if;

use foreign_types::{ForeignType, ForeignTypeRef};

use libc::{c_int, c_long};

use std::cmp;

use std::cmp::{self, Ordering};

use std::error::Error;

use std::ffi::{CStr, CString};

use std::fmt;

        }

    }

    /// Compare two names, like [`Ord`] but it may fail.

    ///

    /// With OpenSSL versions from 3.0.0 this may return an error if the underlying `X509_NAME_cmp`

    /// call fails.

    /// For OpenSSL versions before 3.0.0 it will never return an error, but due to a bug it may

    /// spuriously return `Ordering::Less` if the `X509_NAME_cmp` call fails.

    #[corresponds(X509_NAME_cmp)]

    pub fn try_cmp(&self, other: &X509NameRef) -> Result<Ordering, ErrorStack> {

        let cmp = unsafe { ffi::X509_NAME_cmp(self.as_ptr(), other.as_ptr()) };

        if cfg!(ossl300) && cmp == -2 {

            return Err(ErrorStack::get());

        }

        Ok(cmp.cmp(&0))

    }

    to_der! {

        /// Serializes the certificate into a DER-encoded X509 name structure.

        ///

use std::cmp::Ordering;

use crate::asn1::Asn1Time;

use crate::bn::{BigNum, MsbOption};

use crate::hash::MessageDigest;

        );

    }

}

#[test]

fn test_name_cmp() {

    let cert = include_bytes!("../../test/cert.pem");

    let cert = X509::from_pem(cert).unwrap();

    let subject = cert.subject_name();

    let issuer = cert.issuer_name();

    assert_eq!(Ordering::Equal, subject.try_cmp(subject).unwrap());

    assert_eq!(Ordering::Greater, subject.try_cmp(issuer).unwrap());

}