pub type X509V3_EXT_D2I = Option<unsafe extern "C" fn(*mut c_void, *mut *const u8, i64) -> *mut c_void>;
enum X509V3_EXT_D2I { None, Some(unsafe extern "C" fn(*mut c_void, *mut *const u8, i64) -> *mut c_void), }
No value.
Some value of type T.
T