pub type PFNGLGETPATHCOLORGENFVNVPROC = Option<unsafe extern "C" fn(color: GLenum, pname: GLenum, value: *mut GLfloat)>;
enum PFNGLGETPATHCOLORGENFVNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: *mut f32)), }
No value.
Some value of type T.
T