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#serial 1002
dnl Copyright (C) 2003 Free Software Foundation, Inc.
dnl This file is free software, distributed under the terms of the GNU
dnl General Public License. As a special exception to the GNU General
dnl Public License, this file may be distributed as part of a program
dnl that contains a configuration script generated by Autoconf, under
dnl the same distribution terms as the rest of that program.
# This macro can be removed once we can rely on Autoconf 2.57a or later,
# since we can then use its AC_C_RESTRICT.
# gl_C_RESTRICT
# --------------
# 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,
# define "restrict" to be that. Here are some variants:
# - GCC supports both __restrict and __restrict__
# - older DEC Alpha C compilers support only __restrict
# - _Restrict is the only spelling accepted by Sun WorkShop 6 update 2 C
# Otherwise, define "restrict" to be empty.
AC_DEFUN([gl_C_RESTRICT],
[AC_CACHE_CHECK([for C/C++ restrict keyword], gl_cv_c_restrict,
[gl_cv_c_restrict=no
# Try the official restrict keyword, then gcc's __restrict, and
# the less common variants.
for ac_kw in restrict __restrict __restrict__ _Restrict; do
AC_COMPILE_IFELSE([AC_LANG_SOURCE(
[float * $ac_kw x;])],
[gl_cv_c_restrict=$ac_kw; break])
done
])
case $gl_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, $gl_cv_c_restrict) ;;
esac
])
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