Update m4 macro to provide __UNUSED__.

SVN revision: 38387

1 files changed, 42 insertions, 10 deletions

diff --git a/m4/ac_attribute.m4 b/m4/ac_attribute.m4
index 46c1a42..34bb4db 100644
--- a/m4/ac_attribute.m4
+++ b/m4/ac_attribute.m4
@@ -1,14 +1,46 @@
+dnl Copyright (C) 2004-2008 Kim Woelders
+dnl Copyright (C) 2008 Vincent Torri <vtorri at univ-evry dot fr>
+dnl That code is public domain and can be freely used or copied.
+dnl Originally snatched from somewhere...
+
+dnl Macro for checking if the compiler supports __atribute__
+
+dnl Usage: AC_C___ATTRIBUTE__
+dnl call AC_DEFINE for HAVE___ATTRIBUTE__ and __UNUSED__
+dnl if the compiler supports __attribute__, HAVE___ATTRIBUTE__ is
+dnl defined to 1 and __UNUSED__ is defined to __attribute__((unused))
+dnl otherwise, HAVE___ATTRIBUTE__ is not defined and __UNUSED__ is
+dnl defined to nothing.
 
 AC_DEFUN([AC_C___ATTRIBUTE__],
 [
-  AC_MSG_CHECKING(for __attribute__)
-  AC_CACHE_VAL(ac_cv___attribute__, [
-  AC_TRY_COMPILE([#include <stdlib.h>],
-  [int func(int x); int foo(int x __attribute__ ((unused))) { exit(1); }],
-  ac_cv___attribute__=yes, ac_cv___attribute__=no)])
-  if test "$ac_cv___attribute__" = "yes"; then
-    AC_DEFINE(HAVE___ATTRIBUTE__, 1, [Define to 1 if your compiler has __attribute__])
-  fi
-  AC_MSG_RESULT($ac_cv___attribute__)
-])
 
+AC_MSG_CHECKING([for __attribute__])
+
+AC_CACHE_VAL([ac_cv___attribute__],
+   [AC_TRY_COMPILE(
+       [
+#include <stdlib.h>
+       ],
+       [
+int func(int x);
+int foo(int x __attribute__ ((unused)))
+{
+   exit(1);
+}
+       ],
+       [ac_cv___attribute__="yes"],
+       [ac_cv___attribute__="no"]
+    )]
+)
+
+AC_MSG_RESULT($ac_cv___attribute__)
+
+if test "x${ac_cv___attribute__}" = "xyes" ; then
+   AC_DEFINE([HAVE___ATTRIBUTE__], [1], [Define to 1 if your compiler has __attribute__])
+   AC_DEFINE([__UNUSED__], [__attribute__((unused))], [Macro declaring a function argument to be unused])
+  else
+    AC_DEFINE([__UNUSED__], [], [Macro declaring a function argument to be unused])
+fi
+
+])