Note that it is a bug if you can write your own better black_box

Author: saethlin

library/core/src/hint.rs

@@ -322,6 +322,11 @@ pub fn spin_loop() {
 ///
 /// </div>
 ///
+/// You should not be able to write a better `black_box` than the standard library provides. If you
+/// can write a function that looks like `black_box` but is more effective at hiding the value of
+/// the argument from optimizations, that would be a bug and should be reported. It just would not
+/// be a *security* bug.
+///
 /// [`std::convert::identity`]: crate::convert::identity
 ///
 /// # When is this useful?