On 12/27/2010 09:35 AM, Peter O'Gorman wrote:
> We patch our autoconf to not add -xc99=all to avoid the issue.
Looking at the Autoconf history, Autoconf uses -xc99=all rather than
plain -xc99 because plain -xc99 broke Forte Developer 7 C on Solaris 9:
the compiler assumed C99 semantics for library functions, but the library
didn't do that. I can't remember what went exactly went wrong in that case
and no longer have access to a Solaris 9 box to try it out. I don't think
that particular combination matters much, as nobody uses Forte Developer 7
any more.
On Oracle Solaris Studio 12.2's C compiler, plain -xc99 implies
-xc99=all, and omitting -xc99 entirely implies -xc99='all,no_lib'.
The "no_lib" behavior avoids the problem with __xpg4, but unfortunately
"no_lib" also breaks <stdbool.h>: when one uses no_lib (either
explicitly or implicitly) then the following program:
#include <stdbool.h>
int main (void) { return false; }
causes cc to complain:
"/usr/include/stdbool.h", line 42: #error: "Use of <stdbool.h> is valid only in a c99 compilation environment."
which is silly pedanticism. Programs that use gnulib's
stdbool module work around this problem by supplying their own
stdbool.h, but Autoconf shouldn't be assuming gnulib.
I looked into this a bit, and decided that the easiest way out is to
add -D_STDC_C99= to the command line (instead of -xc99=whatever).
This avoids -xc99's problem of changing the library semantics,
and supports C99 well enough so that Autoconf's test program passes,
which is probably good enough.
I pushed this into Autoconf. Comments welcome.
>From 4e33814cce87f13873c7b9dd5a327fce4c98f2ca Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@xxxxxxxxxxx>
Date: Mon, 27 Dec 2010 23:31:43 -0800
Subject: [PATCH] autoconf: Use -D_STDC_C99=, not -xc99=all, with Solaris cc
* lib/autoconf/c.m4 (_AC_PROG_CC_C99): Use -D_STDC_C99= rather than
-xc99=all to convince Solaris Studio cc to compile c99 programs.
---
ChangeLog | 6 ++++++
lib/autoconf/c.m4 | 15 ++++++++++++---
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index c1ec95d..8c9b89f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-12-27 Paul Eggert <eggert@xxxxxxxxxxx>
+
+ autoconf: Use -D_STDC_C99=, not -xc99=all, with Solaris cc
+ * lib/autoconf/c.m4 (_AC_PROG_CC_C99): Use -D_STDC_C99= rather than
+ -xc99=all to convince Solaris Studio cc to compile c99 programs.
+
2010-11-26 Paul Eggert <eggert@xxxxxxxxxxx>
autotest: fix file descriptor leak
diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4
index a873ccd..5479056 100644
--- a/lib/autoconf/c.m4
+++ b/lib/autoconf/c.m4
@@ -1340,11 +1340,20 @@ dnl AIX -qlanglvl=extc99 (unused restrictive mode: -qlanglvl=stdc99)
dnl HP cc -AC99
dnl Intel ICC -std=c99, -c99 (deprecated)
dnl IRIX -c99
-dnl Solaris -xc99=all (Forte Developer 7 C mishandles -xc99 on Solaris 9,
-dnl as it incorrectly assumes C99 semantics for library functions)
+dnl Solaris -D_STDC_C99=
+dnl cc's -xc99 option uses linker magic to define the external
+dnl symbol __xpg4 as if by "int __xpg4 = 1;", which enables C99
+dnl behavior for C library functions. This is not wanted here,
+dnl because it means that a single module compiled with -xc99
+dnl alters C runtime behavior for the entire program, not for
+dnl just the module. Instead, define the (private) symbol
+dnl _STDC_C99, which suppresses a bogus failure in <stdbool.h>.
+dnl The resulting compiler passes the test case here, and that's
+dnl good enough. For more, please see the thread starting at:
+dnl http://lists.gnu.org/archive/html/autoconf/2010-12/msg00059.html
dnl Tru64 -c99
dnl with extended modes being tried first.
-[[-std=gnu99 -std=c99 -c99 -AC99 -xc99=all -qlanglvl=extc99]], [$1], [$2])[]dnl
+[[-std=gnu99 -std=c99 -c99 -AC99 -D_STDC_C99= -qlanglvl=extc99]], [$1], [$2])[]dnl
])# _AC_PROG_CC_C99
--
1.7.2
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