pub type dyn_MEM_realloc_fn = Option<unsafe extern "C" fn(*mut c_void, usize, *const i8, i32) -> *mut c_void>;
enum dyn_MEM_realloc_fn { None, Some(unsafe extern "C" fn(*mut c_void, usize, *const i8, i32) -> *mut c_void), }
No value.
Some value of type T.
T