Re: Detection of ISO C89 compiler

[Paul Eggert]

On 11/19/2010 03:49 AM, Patrick Pelissier wrote:
>  But I still wonder why the test detecting an ISO C89 compiler
>  uses sys/types.h and sys/stat.h.

I expect it's an oversight.  That test was stolen from RCS 5.7, dated
1995, which assumed a POSIX-like environment.  I installed
the following patch to fix things.  Thanks for reporting the problem.

(It's vaguely possible that some ancient system failed to compile
sys/stat.h when in C89 mode, and that this was part of the test,
but if so, I doubt whether that's worth worrying about these days.)

>From 5ad7787f1967341cf356f9c3bd11c59f04a82d82 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Sat, 20 Nov 2010 15:26:39 -0800
Subject: [PATCH] autoconf: don't assume sys/stat.h and sys/types.h when testing 
C89

Problem reported by Patrick Pelissier in
<http://lists.gnu.org/archive/html/bug-autoconf/2010-11/msg00019.html>.
* lib/autoconf/c.m4 (_AC_PROG_CC_C89): Don't include sys/types.h
and sys/stat.h.  Instead, define a dummy struct stat.  C89 doesn't
guarantee sys/types.h and sys/stat.h.
---
 ChangeLog         |    9 +++++++++
 lib/autoconf/c.m4 |    3 +--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index e34119c..62358ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2010-11-20  Paul Eggert  <address@hidden>
+
+       autoconf: don't assume sys/stat.h and sys/types.h when testing C89
+       Problem reported by Patrick Pelissier in
+       <http://lists.gnu.org/archive/html/bug-autoconf/2010-11/msg00019.html>.
+       * lib/autoconf/c.m4 (_AC_PROG_CC_C89): Don't include sys/types.h
+       and sys/stat.h.  Instead, define a dummy struct stat.  C89 doesn't
+       guarantee sys/types.h and sys/stat.h.
+
 2010-11-10  Reuben Thomas  <address@hidden>  (tiny change)
 
        docs: avoid first person, and credit history to David MacKenzie
diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4
index 233644a..a873ccd 100644
--- a/lib/autoconf/c.m4
+++ b/lib/autoconf/c.m4
@@ -1102,8 +1102,7 @@ AC_DEFUN([_AC_PROG_CC_C89],
 [_AC_C_STD_TRY([c89],
 [[#include <stdarg.h>
 #include <stdio.h>
-#include <sys/types.h>
-#include <sys/stat.h>
+struct stat;
 /* Most of the following tests are stolen from RCS 5.7's src/conf.sh.  */
 struct buf { int x; };
 FILE * (*rcsopen) (struct buf *, struct stat *, int);
-- 
1.7.2