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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
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Autoconf Macro: ac_check_cc_opt
</title>
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<hr>
<h1>
ac_check_cc_opt
</h1>
<h2>
Obsolete Macro
</h2>
<p class="indent">
Use CFLAGS/CXXFLAGS related macros as soon as possible.
</p>
<h2>
Synopsis
</h2>
<p class="indent" style="white-space:nowrap;">
<code>AC_CHECK_CC_OPT(flag, cachevarname)</code>
</p>
<h2>
Description
</h2>
<div class="indent">
<p>
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_@.
</p>
<p>
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.
</p>
<p>
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.
</p>
</div>
<h2>
Author
</h2>
<p class="indent">
Guido Draheim <guidod@gmx.de>
</p>
<h2>
Last Modified
</h2>
<p class="indent">
2005-01-25
</p>
<h2>
M4 Source Code
</h2>
<div class="indent">
<pre class="m4source">
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*
])])
</pre>
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