Comment by isaacimagine

See 'Reflections on Rusting Trust' by Manish Goregaokar (In Pursuit of Laziness).

https://manishearth.github.io/blog/2016/12/02/reflections-on...

He modifies rustc with a predicate that replaces the string 'hello world' with something else. The method used to replicate the change is basically a self-modifying quine.