cdefs(9): document __nonstring

[mhorne]

Summary

Fixes: 802c6d5d61d1 ("cdefs.h: Introduce __nonstring attribute")
MFC after: 3 days
Sponsored by: The FreeBSD Foundation

[imp]

share/man/man9/cdefs.9

210

Do we use null for the 0 character or NUL? I'm more used to the latter.

[mhorne]

Prefer .Dv NUL and bump .Dd.

[mhorne]

share/man/man9/cdefs.9

210

Absolutely! This seems to be the precedent. Updating.

[emaste]

share/man/man9/cdefs.9

210

I believe "null terminator" or "null-terminated string" are conventional, and NUL if we specifically want to refer to an ASCII control character.

We have a mix of "null terminator", "nul terminator", and "NUL terminator" in the tree today. The middle one seems completely wrong.

[emaste]

C11 uses "null terminator" or "null terminated" and has this text

A byte with all bits set to 0, called the null character, shall exist in the basic execution character set; it is used to terminate a character string.

[emaste]

Oops, clicking accept crossed paths with the update.

I'm fine with the current version (.Dv NUL terminator) if that's what you want to go with, but I think that "does not require a null terminator" or "is not a null-terminated string" is preferable.

[imp]

I asked as a question to learn the latest. I'm cool with what's there or c11 usage

[mhorne]

In D58804#1349329, @emaste wrote:

Oops, clicking accept crossed paths with the update.

I'm fine with the current version (.Dv NUL terminator) if that's what you want to go with, but I think that "does not require a null terminator" or "is not a null-terminated string" is preferable.

Thanks for looking further. I will revert to the previous version, then.