Would you like signs with those chars?

Would you like signs with those chars?

Sure, but standard doesn't say what compiler (or, even worse non-compiler) have to do with broken programs.

And if you ignore what standard says and just go with isalpha/isalnum + Unicode (where Unicode == “high bit is set”) then you would handle all correct programs perfectly. And if someone feeds incorrect one… who cares how would it be handled?

It's not as if we live in a world where everyone cares all that much about following the standard to a T.