pub type OSSL_FUNC_cleanup_nonce_fn = Option<unsafe extern "C" fn(*const ossl_core_handle_st, *mut u8, usize)>;
enum OSSL_FUNC_cleanup_nonce_fn { None, Some(unsafe extern "C" fn(*const ossl_core_handle_st, *mut u8, usize)), }
No value.
Some value of type T.
T