Re: Use of feature test macros
Robert Elz <[email protected]>
| Newsgroups | gmane.os.netbsd.devel.userlevel |
|---|---|
| Message-ID | <[email protected]> |
Date: Sat, 2 Nov 2024 22:36:10 +0100
From: Roland Illig <[email protected]>
Message-ID: <[email protected]>
| In the system headers, we use this pattern a lot:
| > #if (_POSIX_C_SOURCE - 0 >= 200809L) || defined(_NETBSD_SOURCE)
|
| Are the parentheses around the first condition really necessary? If so,
| for which cases?
Do they hurt? Parens generally make it easier to read exprs like
this, within reason, almost never harder.
| Is the "- 0" in the first expression really necessary? If so, for which
| cases?
When _POSIX_C_SOURCE is undefined (or defined to nothing).
That is the standard idiom for testing all of these feature macros.
kre