Any language that does it, is beyond usable (notably go and zig). Like, I would literally fork the compiler before using them with that “feature” on. It’s completely braindead thing to do — like okay, have a separate production release mode and make it an error there. But for quickly testing out stuff, you will inevitably comment something out, which makes a variable unused. Commenting that out will also make something else unused, so you literally have a recursive problem with some random depth, and depending on how deep it goes, you will literally lose all of the context on what you wanted to debug in the first place.

There is literally zero advantage of this idiotic bullshit, my proposed solution of doing it only in prod release gives all the benefits with none of the negatives.