Whence '\n'?

Whence '\n'?, by Casey Rodarmor is a very short entry on a seemingly uninteresting topic: how does rustc (the rust compiler) know that the binary code for \n is 0x0A? Of course, we all know that \n is 0x0A because it's the ASCII code for the newline character, but when looking for such a mapping in rustc's source code, we find none. The actual answer is that the ocaml compiler contains the line 'n' -> '\010', the ocaml compiler then compiled the first rust compiler (written in ocaml), embuing it with this knowledge. The ocaml rust compiler then compiled rustc and passed that knowledge on. And since rustc 1.0 the last version passes it on to the next rustc version. Deeper than you thought, huh?

From the article:

rustc is currently at version 1.81.0, so this has happened at least 81 times since rustc 1.0 was first released, and probably many more times than that before 1.0, with rustcs furtively smuggling 0x0A bytes from one to the other, all the way back to when it was written in OCaml, when finally the first 0x0A byte was stuffed into a rustc binary by the OCaml compiler, which evaluated it from a decimal character escape '\010'.

This is closely related to the behavior presented in Ken Thompson's famous Turing Award Lecture Reflections on Trusting Trust, just not as dangerous.