##### http://autoconf-archive.cryp.to/ac_check_cc_opt.html
#
# OBSOLETE MACRO
#
#   Use CFLAGS/CXXFLAGS related macros as soon as possible.
#
# SYNOPSIS
#
#   AC_CHECK_CC_OPT(flag, cachevarname)
#
# DESCRIPTION
#
#   AC_CHECK_CC_OPT(-fvomit-frame,vomitframe) would show a message as
#   like "checking wether gcc accepts -fvomit-frame ... no" and sets
#   the shell-variable $vomitframe to either "-fvomit-frame" or (in
#   this case) just a simple "". In many cases you would then call
#   AC_SUBST(_fvomit_frame_,$vomitframe) to create a substitution that
#   could be fed as "CFLAGS = @_funsigned_char_@ @_fvomit_frame_@.
#
#   In consequence this function is much more general than their
#   specific counterparts like ac_cxx_rtti.m4 that will test for
#   -fno-rtti -fno-exceptions.
#
#   This macro will be obsolete in the very near future - there should
#   be two macros AX_CFLAGS_OPTION and AX_CXXFLAGS_OPTION that will add
#   directly to the CFLAGS/CXXFLAGS unless a ac_subst-variable was
#   given. Remind me of doing so if I forget about writing it all up -
#   to use $CC-cc directly in here instead of ac_compile macro is bad
#   anyway.
#
# LAST MODIFICATION
#
#   2006-10-13
#
# COPYLEFT
#
#   Copyright (c) 2006 Guido U. Draheim <guidod@gmx.de>
#
#   This program is free software; you can redistribute it and/or
#   modify it under the terms of the GNU General Public License as
#   published by the Free Software Foundation; either version 2 of the
#   License, or (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful, but
#   WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
#   General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
#   02111-1307, USA.
#
#   As a special exception, the respective Autoconf Macro's copyright
#   owner gives unlimited permission to copy, distribute and modify the
#   configure scripts that are the output of Autoconf when processing
#   the Macro. You need not follow the terms of the GNU General Public
#   License when using or distributing such scripts, even though
#   portions of the text of the Macro appear in them. The GNU General
#   Public License (GPL) does govern all other use of the material that
#   constitutes the Autoconf Macro.
#
#   This special exception to the GPL applies to versions of the
#   Autoconf Macro released by the Autoconf Macro Archive. When you
#   make and distribute a modified version of the Autoconf Macro, you
#   may extend this special exception to the GPL to apply to your
#   modified version as well.

AC_DEFUN([AC_CHECK_CC_OPT],
[AC_CACHE_CHECK(whether ${CC-cc} accepts [$1], [$2],
[AC_SUBST($2)
echo 'void f(){}' > conftest.c
if test -z "`${CC-cc} -c $1 conftest.c 2>&1`"; then
  $2="$1"
else
  $2=""
fi
rm -f conftest*
])])