svn commit: r295561 - in head: include sys/mips/include sys/powerpc/include sys/sparc64/include sys/sys sys/x86/include

[Konstantin Belousov]

On Sat, Feb 13, 2016 at 03:56:42AM +1100, Bruce Evans wrote:
> Our Standard C namespace is a subset of the POSIX namespace.  Most
> Standard C headers are (were) careful about this.  There aren't many
> Standard C headers or versions of Standard C or large variations in the
> versions, so this is relatively easy to do.
> 
> We also attempt to use POSIX visibility ifdefs.  This is not done so
> carefully, and has more bugs due to more variations.  But <signal.h>
> does it fairly carefully.  It has ifdefs for XSI, POSIX >= 2001,
> any-POSIX (this is now very broken by unconditional declarations for
> pthreads), POSIX >= 1995 (realtime POSIX stuff which I think was
> standardized in POSIX.4 (.1b?) a couple of years before 1995, but we
> don't have ifdefs for that), POSIX >= 2008 (psignal).  That is just
> in the top-level header.  Almost half of that is only under XSI or
> BSD, and it is quite likely that some newer or older POSIX or XSI
> things are under the wrong ifdefed but are usually visible because
> everything is visible by default.  sys/signal.h has ifdefs for
> POSIX >= 1993, more-delicate version ifdefs for XSI and POSIX <= 2001.
> Most of the POSIX >= 1993 ifdefs are for realtime POSIX stuff.  An
> enormous number of definitions for things like trap codes for FP errors
> are misplaced under the POSIX >= 1993 || XSI ifdef.  These weren't in
> POSIX.1-2006.  This contrasts with the fine-grained ifdefs for signal
> numbers.
> 
> I find the ifdefs useful for seeing when POSIX introduced a feature
> but not for actual use to compile under an old standard.

So you are about the ANSI C & non-POSIX compilation environment ?
Do you mean the following:

diff --git a/include/signal.h b/include/signal.h
index 33be55c..31cded7 100644
--- a/include/signal.h
+++ b/include/signal.h
@@ -36,8 +36,10 @@
 #include <sys/cdefs.h>
 #include <sys/_types.h>
 #include <sys/signal.h>
+#if __POSIX_VISIBLE || __XSI_VISIBLE
 #include <machine/ucontext.h>
 #include <sys/_ucontext.h>
+#endif
 
 #if __BSD_VISIBLE
 /*

I can change #if __POSIX_VISIBLE to some version cap, if you prefer.