Avoid gcc warnings because of #pragma GCC system_header on older gcc.

diff --git a/ChangeLog b/ChangeLog
index d85acea73816b1b9ea0cb805f48528d2c4453440..4e10e2a8aeb8eb9bc709b3ab2d1ab6fd92fb5f02 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2008-10-17  Bruno Haible  <bruno@clisp.org>
+
+       Avoid gcc warnings because of #pragma GCC system_header on older gcc.
+       * m4/include_next.m4: Require autoconf >= 2.60.
+       (gl_INCLUDE_NEXT): Use #pragma GCC system_header only for GCC 3.0 or
+       newer.
+       Reported by Yoann Vandoorselaere <yoann.v@prelude-ids.com>.
+
 2008-10-17  Jim Meyering  <meyering@redhat.com>
 
        ignore-value: don't depend on inline module

diff --git a/m4/include_next.m4 b/m4/include_next.m4
index b6e4d3ae7a92c2e1a7c83b5325a31fadf25f8ff7..91ecbb0965a2f6eee78fb96c6e99310860b180f3 100644 (file)
--- a/m4/include_next.m4
+++ b/m4/include_next.m4
@@ -1,4 +1,4 @@
-# include_next.m4 serial 8
+# include_next.m4 serial 9
 dnl Copyright (C) 2006-2008 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,6 +6,8 @@ dnl with or without modifications, as long as this notice is preserved.
 
 dnl From Paul Eggert and Derek Price.
 
+AC_PREREQ([2.60])
+
 dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER.
 dnl
 dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
@@ -59,7 +61,10 @@ EOF
   if test $gl_cv_have_include_next = yes; then
     INCLUDE_NEXT=include_next
     if test -n "$GCC"; then
-      PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
+      dnl GCC 3.0 or newer supports #pragma GCC system_header.
+      PRAGMA_SYSTEM_HEADER='#if __GNUC__ >= 3
+#pragma GCC system_header
+#endif'
     fi
   else
     INCLUDE_NEXT=include