/[autoconf]/autoconf/lib/autoconf/c.m4
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revision 1.175 by eggert, Thu Mar 6 20:35:23 2003 UTC revision 1.176 by meyering, Sat Apr 12 20:53:20 2003 UTC
# Line 1  Line 1 
1  # This file is part of Autoconf.                       -*- Autoconf -*-  # This file is part of Autoconf.                       -*- Autoconf -*-
2  # Programming languages support.  # Programming languages support.
3  # Copyright (C) 2001, 2002 Free Software Foundation, Inc.  # Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
4  #  #
5  # This program is free software; you can redistribute it and/or modify  # This program is free software; you can redistribute it and/or modify
6  # it under the terms of the GNU General Public License as published by  # it under the terms of the GNU General Public License as published by
# Line 1077  fi Line 1077  fi
1077  ])# AC_C_CONST  ])# AC_C_CONST
1078    
1079    
1080    # AC_C_RESTRICT
1081    # -------------
1082    # based on acx_restrict.m4, from the GNU Autoconf Macro Archive at:
1083    # http://www.gnu.org/software/ac-archive/htmldoc/acx_restrict.html
1084    #
1085    # Determine whether the C/C++ compiler supports the "restrict" keyword
1086    # introduced in ANSI C99, or an equivalent.  Do nothing if the compiler
1087    # accepts it.  Otherwise, if the compiler supports an equivalent,
1088    # define "restrict" to be that.  Here are some variants:
1089    # - GCC supports both __restrict and __restrict__
1090    # - older DEC Alpha C compilers support only __restrict
1091    # - _Restrict is the only spelling accepted by Sun WorkShop 6 update 2 C
1092    # Otherwise, define "restrict" to be empty.
1093    AN_IDENTIFIER([restrict], [AC_C_RESTRICT])
1094    AC_DEFUN([AC_C_RESTRICT],
1095    [AC_CACHE_CHECK([for C/C++ restrict keyword], ac_cv_c_restrict,
1096      [ac_cv_c_restrict=no
1097       # Try the official restrict keyword, then gcc's __restrict__, and
1098       # the less common variants.
1099       for ac_kw in restrict __restrict __restrict__ _Restrict; do
1100         AC_COMPILE_IFELSE([AC_LANG_SOURCE(
1101          [float * $ac_kw x;])],
1102          [ac_cv_c_restrict=$ac_kw; break])
1103       done
1104      ])
1105     case $ac_cv_c_restrict in
1106       restrict) ;;
1107       no) AC_DEFINE(restrict,,
1108            [Define to equivalent of C99 restrict keyword, or to nothing if this
1109            is not supported.  Do not define if restrict is supported directly.]) ;;
1110       *)  AC_DEFINE_UNQUOTED(restrict, $ac_cv_c_restrict) ;;
1111     esac
1112    ])# AC_C_RESTRICT
1113    
1114    
1115  # AC_C_VOLATILE  # AC_C_VOLATILE
1116  # -------------  # -------------
1117  # Note that, unlike const, #defining volatile to be the empty string can  # Note that, unlike const, #defining volatile to be the empty string can

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