pub type PFNGLIMPORTSEMAPHOREFDEXTPROC = Option<unsafe extern "C" fn(semaphore: GLuint, handleType: GLenum, fd: GLint)>;
enum PFNGLIMPORTSEMAPHOREFDEXTPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: i32)), }
No value.
Some value of type T.
T