pub type sk_BIO_cmp_func = Option<unsafe extern "C" fn(arg1: *const *const BIO, arg2: *const *const BIO) -> c_int>;
enum sk_BIO_cmp_func { None, Some(unsafe extern "C" fn(*const *const bio_st, *const *const bio_st) -> i32), }
No value.
Some value of type T.
T