pub type PFNGLSTENCILFILLPATHNVPROC = Option<unsafe extern "C" fn(path: GLuint, fillMode: GLenum, mask: GLuint)>;
enum PFNGLSTENCILFILLPATHNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: u32)), }
No value.
Some value of type T.
T