#serial 1001
dnl based on acx_restrict.m4, from the GNU Autoconf Macro Archive at:
dnl http://www.gnu.org/software/ac-archive/htmldoc/acx_restrict.html

# Determine whether the C/C++ compiler supports the "restrict" keyword
# introduced in ANSI C99, or an equivalent.  Do nothing if the compiler
# accepts it.  Otherwise, if the compiler supports an equivalent (like
# gcc's __restrict__) define "restrict" to be that.  Otherwise, define
# "restrict" to be empty.

AC_DEFUN([ACX_C_RESTRICT],
[AC_CACHE_CHECK([for C/C++ restrict keyword], acx_cv_c_restrict,
  [acx_cv_c_restrict=no
   # Try the official restrict keyword, then gcc's __restrict__.
   for acx_kw in restrict __restrict__; do
     AC_COMPILE_IFELSE([AC_LANG_SOURCE(
      [float * $acx_kw x;])],
      [acx_cv_c_restrict=$acx_kw; break])
   done
  ])
 case $acx_cv_c_restrict in
   restrict) ;;
   no) AC_DEFINE(restrict,,
	[Define to equivalent of C99 restrict keyword, or to nothing if this
	is not supported.  Do not define if restrict is supported directly.]) ;;
   *)  AC_DEFINE_UNQUOTED(restrict, $acx_cv_c_restrict) ;;
 esac
])