AC_CHECK_CC_OPT(flag, cachevarname)
, 

2005-01-25

Guido U. Draheim <guidod@gmx.de>

GPLWithACException
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. 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

guidod's Obsoleted (obsoleted)

• obsoleted Use CFLAGS/CXXFLAGS related macros as soon as possible.

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.

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*
])])