Re: Re: Best bikeshed ever (feature test macros)

[Isaac Dunham <idunham@lavabit.com>]

On Wed, 29 Aug 2012 10:01:29 -0400
Gregor Richards <gr@purdue.edu> wrote:

> On 08/29/2012 09:49 AM, Rich Felker wrote:
> > On Wed, Aug 29, 2012 at 07:34:42AM +0200, philomath wrote:
> >> On Fri, 24 Aug 2012 17:41:38 -0400
> >> Rich Felker <dalias@aerifal.cx> wrote:
> >>
> >>
> >>> 1. Leaving everything as it is.
> >>> 2. Making the kitchen sink (_GNU_SOURCE) available by default.
> >>> 3. Making only some limited subset (e.g. POSIX base) available by
> >>> default.
> >> The bikeshed should definitely not be colored black.
> >>
> >> I'd lean towards 3, 1 is fine too. but please not 2, musl's
> >> correctness is one of it's unique features...

Agreed..._GNU_SOURCE is the kitchen sink _and_ the garbage can as well.

> _XOPEN_SOURCE=700 has the advantage that it does include lots of
> things, and is a standard, so it's not an arbitrary moving target.
> It's probably not sufficient, but I'm not wholly convinced of that.

I said _XOPEN_SOURCE=600, with musl's behavior (equivalent to
_XOPEN_SOURCE=700 + obsolete extensions). There are a few extensions
that occasionally pop up.

> _BSD_SOURCE (which on musl apparently implies _XOPEN_SOURCE, which
> makes sense since it's not like they're not trying) is better, the
> only reason I don't like it is that it's not a standard, so there's
> no clear demarcation of what it could imply, and arbitrary new things
> from the BSDs could be added at any point. 
When I prepared the patch, I followed _NETBSD_SOURCE on current-ish
NetBSD.
It does (did?) not _necessarily_ imply _XOPEN_SOURCE, but there are few
places where NetBSD does not make X/Open 700 functionality available.

HTH,
Isaac Dunham