Comment by Joker_vD

Now, my toy programming languages all share the same "ensureCharLegal" function in their lexers that's called on every single character in the input (including those inside the literal strings) that filters out all those characters, plus all control characters (except the LF), and also something else that I can't remember right now... some weird space-like characters, I think?

Nothing really stops the non-toy programming and configuration languages from adopting the same approach except from the fact that someone has to think about it and then implement it.