pub type PFNGLGETINTEGERUI64I_VNVPROC = Option<unsafe extern "C" fn(value: GLenum, index: GLuint, result: *mut GLuint64EXT)>;
enum PFNGLGETINTEGERUI64I_VNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: *mut u64)), }
No value.
Some value of type T.
T