pub type PFNGLPROGRAMUNIFORM1I64NVPROC = Option<unsafe extern "C" fn(program: GLuint, location: GLint, x: GLint64EXT)>;
enum PFNGLPROGRAMUNIFORM1I64NVPROC { None, Some(unsafe extern "C" fn(_: u32, _: i32, _: i64)), }
No value.
Some value of type T.
T