[zedshaw]

> It's unsafe in exactly the same way that the unsafe copy() function is

No, that's the logic error every programmer makes. The copy() function is always wrong, because it can't confirm that the string has the right length without looking at the string which causes the error.

With my function I can go to as great a length as I want to confirm that the string is actually as long as I say it is. I can't mitigate every possible error of misuse, but the errors safercopy() can have are much smaller than copy().

Your argument is effectively stating that because you can exploit one with a general "UB" error, that it's the same size and classification of errors as with the other. That's invalid, and proven in my writing.