But it doesn't have a (native) switch.
No fair, picking on explicit design decisions. :-)
Warn (wrongly) for one particular function
What's wrong about the warning? It's there to prevent the common pitfall of expecting things like this to work right:
And seems like a perfectly reasonable warning. Many other warnings are special-cased and very specific, so I don't know why you chose this one.
Update: I didn't realize the warning would trigger with one and only one space. That does seem kind of peculiar. But if that was the crux of what the OP was talking about, it wasn't exactly clear.