[PATCH] __FreeBSD_kernel__

[Robert Millan]

2011/7/3 Alexander Kabaev <kabaev at gmail.com>:
> I do not think this belongs in GCC at all. You should already have a
> defined symbol to identify your OS and that should be used in cases
> where it matters.

If we wanted to identify the OS as a whole, we can currently do this
with something like:

"#if defined(__FreeBSD_kernel__) && defined(__GLIBC__)"

however, in practice this never happens.  What almost every check
wants is either to know about our userland APIs (hence __GLIBC__) or
to know about our kernel APIs (then __FreeBSD_kernel__).

In both cases, the check also wants to match other operating systems
(FreeBSD when it comes to kernel API checks, and GNU/{Linux,Hurd} when
it comes to userland API checks).  Using macros that are shared (like
__GLIBC__) or that could potentially be shared (like
__FreeBSD_kernel__) with other operating systems maximizes the
opportunities to:

a) produce simpler checks like "#ifdef __GLIBC__" which are easier to
read and maintain.

b) collaborate with other projects by producing patches which have the
collateral effect of improving portability with other operating
systems.

-- 
Robert Millan