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AC_PROG_CC_NO_WRITEABLE_STRINGS(substvar [,hard])
1.4 (2003/02/02) 0.5.57 : guidod
Guido Draheim <guidod@gmx.de>
obsoleted by AX_CFLAGS_NO_WRITABLE_STRINGS
Try to find a compiler option that warns when a stringliteral is used in a place that could potentially modify the address. This should warn on giving an stringliteral to a function that asks of a non-const-modified char-pointer.
The sanity check is done by looking at string.h which has a set of strcpy definitions that should be defined with const-modifiers to not emit a warning in all so many places.
Currently this macro knows about GCC. hopefully will evolve to use: Solaris C compiler, Digital Unix C compiler, C for AIX Compiler, HP-UX C compiler, and IRIX C compiler.
AC_DEFUN([AC_PROG_CC_NO_WRITEABLE_STRINGS], [
pushdef([CV],ac_cv_prog_cc_no_writeable_strings)dnl
hard=$2
if test -z "$hard"; then
msg="C to warn about writing to stringliterals"
else
msg="C to prohibit any write to stringliterals"
fi
AC_CACHE_CHECK($msg, CV, [
cat > conftest.c <<EOF
#include <string.h>
int main (void)
{
char test[[16]];
if (strcpy (test, "test")) return 0;
return 1;
}
EOF
dnl GCC
if test "$GCC" = "yes";
then
if test -z "$hard"; then
CV="-Wwrite-strings"
else
CV="-fno-writable-strings -Wwrite-strings"
fi
if test -n "`${CC-cc} -c $CV conftest.c 2>&1`" ; then
CV="suppressed: string.h"
fi
dnl Solaris C compiler
elif $CC -flags 2>&1 | grep "Xc.*strict ANSI C" > /dev/null 2>&1 &&
$CC -c -xstrconst conftest.c > /dev/null 2>&1 &&
test -f conftest.o
then
# strings go into readonly segment
CV="-xstrconst"
rm conftest.o
if test -n "`${CC-cc} -c $CV conftest.c 2>&1`" ; then
CV="suppressed: string.h"
fi
dnl HP-UX C compiler
elif $CC > /dev/null 2>&1 &&
$CC -c +ESlit conftest.c > /dev/null 2>&1 &&
test -f conftest.o
then
# strings go into readonly segment
CV="+ESlit"
rm conftest.o
if test -n "`${CC-cc} -c $CV conftest.c 2>&1`" ; then
CV="suppressed: string.h"
fi
dnl Digital Unix C compiler
elif ! $CC > /dev/null 2>&1 &&
$CC -c -readonly_strings conftest.c > /dev/null 2>&1 &&
test -f conftest.o
then
# strings go into readonly segment
CV="-readonly_strings"
rm conftest.o
if test -n "`${CC-cc} -c $CV conftest.c 2>&1`" ; then
CV="suppressed: string.h"
fi
dnl C for AIX Compiler
dnl IRIX C compiler
# -use_readonly_const is the default for IRIX C,
# puts them into .rodata, but they are copied later.
# need to be "-G0 -rdatashared" for strictmode but
# I am not sure what effect that has really.
fi
rm -f conftest.*
])
if test -z "[$]$1" ; then
if test -n "$CV" ; then
case "$CV" in
suppressed*) $1="" ;; # known but suppressed
*) $1="$CV" ;;
esac
fi
fi
AC_SUBST($1)
popdef([CV])dnl
])