Re: [RFC/PATCH 1/2] Teach Solaris that _XOPEN_SOURCE=600 really menas XPG6

From: Brandon Casey <casey@nrlssc.navy.mil>
Date: May 28, 2009, 16:46 UTC
Message-ID: <WLNdjYtfqcg2bT6yOBtAykIqOBTeSLRUdlB6-sTM2KzTjwOmzN3fLg@cipher.nrlssc.navy.mil>
In-Reply-To: <1243106697-6424-2-git-send-email-gitster@pobox.com>

Junio C Hamano wrote:

Show 47 quoted lines

> In git-compat-util.h, we do
> 
>     #define _XOPEN_SOURCE 600
>     #define _XOPEN_SOURCE_EXTENDED 1
> 
> unless we are on BSD or SCO.
> 
> On OpenSolaris (200811), /usr/include/sys/feature_tests.h has this nice
> table:
> 
>     Feature Test Macro				     Specification
>     ------------------------------------------------  -------------
>     _XOPEN_SOURCE                                         XPG3
>     _XOPEN_SOURCE && _XOPEN_VERSION = 4                   XPG4
>     _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED = 1           XPG4v2
>     _XOPEN_SOURCE = 500                                   XPG5
>     _XOPEN_SOURCE = 600  (or POSIX_C_SOURCE=200112L)      XPG6
> 
> Later in the same header, compilation with -c99 is made to fail if _XPG6 is
> not set, like this:
> 
>     #if defined(_STDC_C99) && (defined(__XOPEN_OR_POSIX) && !defined(_XPG6))
>     #error "Compiler or options invalid for pre-UNIX 03 X/Open applications \
>             and pre-2001 POSIX applications"
>     #elif ...
> 
> The problem is that they check things in an order that is inconvenient for
> us.  When they see _XOPEN_SOURCE_EXTENDED, they declare that we are XPG4v2,
> regardless of the value of _XOPEN_SOURCE.
> 
> To work around this problem, do not define _XOPEN_SOURCE_EXTENDED on
> Sun's.
> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>  git-compat-util.h |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/git-compat-util.h b/git-compat-util.h
> index c7cf2d5..4236647 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -41,8 +41,10 @@
>  
>  #if !defined(__APPLE__) && !defined(__FreeBSD__)  && !defined(__USLC__) && !defined(_M_UNIX)
>  #define _XOPEN_SOURCE 600 /* glibc2 and AIX 5.3L need 500, OpenBSD needs 600 for S_ISLNK() */
> +#ifndef __sun__

__sun__ is not defined by the SUNWspro compiler. We can fix that by adding a -D__sun__ in the SunOS section of the Makefile though.

A more important issue, is that now that this causes _XPG6 to be defined, sun's header files _require_ a c99 compiler to be used.

Here's the comment that goes along with the partial snippet that you showed above from /usr/include/sys/feature_tests.h:

  /*
   * It is invalid to compile an XPG3, XPG4, XPG4v2, or XPG5 application
   * using c99.  The same is true for POSIX.1-1990, POSIX.2-1992, POSIX.1b,
   * and POSIX.1c applications. Likewise, it is invalid to compile an XPG6
   * or a POSIX.1-2001 application with anything other than a c99 or later
   * compiler.  Therefore, we force an error in both cases.
   */

And the rest of the macro implements the check for source/compiler suitability.

So we either require compiling with a c99 compiler (by ensuring that _XPG6 is set) or exclude compiling with a c99 compiler on sun (by ensuring that _XPG6 is not set). Actually, this would only affect Solaris versions which support XPG6. Solaris 11 and 10 do. I don't know about Solaris 9 and 8. Solaris 7 doesn't.

Which do we want to do?

Show 6 quoted lines

>  #define _XOPEN_SOURCE_EXTENDED 1 /* AIX 5.3L needs this */
>  #endif
> +#endif
>  #define _ALL_SOURCE 1
>  #define _GNU_SOURCE 1
>  #define _BSD_SOURCE 1