pub type PFNGLSETLOCALCONSTANTEXTPROC = Option<unsafe extern "C" fn(id: GLuint, type_: GLenum, addr: *mut c_void)>;
enum PFNGLSETLOCALCONSTANTEXTPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: *mut c_void)), }
No value.
Some value of type T.
T