pub type d2i_of_void = Option<unsafe extern "C" fn(*mut *mut c_void, *mut *const u8, i64) -> *mut c_void>;
enum d2i_of_void { None, Some(unsafe extern "C" fn(*mut *mut c_void, *mut *const u8, i64) -> *mut c_void), }
No value.
Some value of type T.
T