dnl CF_GCC_ATTRIBUTES version: 14 updated: 2010/10/23 15:52:32
dnl -----------------
dnl Test for availability of useful gcc __attribute__ directives to quiet
dnl compiler warnings.  Though useful, not all are supported -- and contrary
dnl to documentation, unrecognized directives cause older compilers to barf.
AC_DEFUN([CF_GCC_ATTRIBUTES],
[
if test "$GCC" = yes
then
cat > conftest.i <<EOF
#ifndef GCC_PRINTF
#define GCC_PRINTF 0
#endif
#ifndef GCC_SCANF
#define GCC_SCANF 0
#endif
#ifndef GCC_NORETURN
#define GCC_NORETURN /* nothing */
#endif
#ifndef GCC_UNUSED
#define GCC_UNUSED /* nothing */
#endif
EOF
if test "$GCC" = yes
then
	AC_CHECKING([for $CC __attribute__ directives])
cat > conftest.$ac_ext <<EOF
#line __oline__ "${as_me:-configure}"
#include "confdefs.h"
#include "conftest.h"
#include "conftest.i"
#if	GCC_PRINTF
#define GCC_PRINTFLIKE(fmt,var) __attribute__((format(printf,fmt,var)))
#else
#define GCC_PRINTFLIKE(fmt,var) /*nothing*/
#endif
#if	GCC_SCANF
#define GCC_SCANFLIKE(fmt,var)  __attribute__((format(scanf,fmt,var)))
#else
#define GCC_SCANFLIKE(fmt,var)  /*nothing*/
#endif
extern void wow(char *,...) GCC_SCANFLIKE(1,2);
extern void oops(char *,...) GCC_PRINTFLIKE(1,2) GCC_NORETURN;
extern void foo(void) GCC_NORETURN;
int main(int argc GCC_UNUSED, char *argv[[]] GCC_UNUSED) { return 0; }
EOF
	cf_printf_attribute=no
	cf_scanf_attribute=no
	for cf_attribute in scanf printf unused noreturn
	do
		CF_UPPER(cf_ATTRIBUTE,$cf_attribute)
		cf_directive="__attribute__(($cf_attribute))"
		echo "checking for $CC $cf_directive" 1>&AC_FD_CC

		case $cf_attribute in #(vi
		printf) #(vi
			cf_printf_attribute=yes
			cat >conftest.h <<EOF
#define GCC_$cf_ATTRIBUTE 1
EOF
			;;
		scanf) #(vi
			cf_scanf_attribute=yes
			cat >conftest.h <<EOF
#define GCC_$cf_ATTRIBUTE 1
EOF
			;;
		*) #(vi
			cat >conftest.h <<EOF
#define GCC_$cf_ATTRIBUTE $cf_directive
EOF
			;;
		esac

		if AC_TRY_EVAL(ac_compile); then
			test -n "$verbose" && AC_MSG_RESULT(... $cf_attribute)
			cat conftest.h >>confdefs.h
			case $cf_attribute in #(vi
			printf) #(vi
				if test "$cf_printf_attribute" = no ; then
					cat >>confdefs.h <<EOF
#define GCC_PRINTFLIKE(fmt,var) /* nothing */
EOF
				else
					cat >>confdefs.h <<EOF
#define GCC_PRINTFLIKE(fmt,var) __attribute__((format(printf,fmt,var)))
EOF
				fi
				;;
			scanf) #(vi
				if test "$cf_scanf_attribute" = no ; then
					cat >>confdefs.h <<EOF
#define GCC_SCANFLIKE(fmt,var) /* nothing */
EOF
				else
					cat >>confdefs.h <<EOF
#define GCC_SCANFLIKE(fmt,var)  __attribute__((format(scanf,fmt,var)))
EOF
				fi
				;;
			esac
		fi
	done
else
	fgrep define conftest.i >>confdefs.h
fi
rm -rf conftest*
fi
])dnl
