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# va_copy.m4 serial 1 (js-1.6.20070208)
dnl ##
dnl ## Check for C99 va_copy() implementation
dnl ## (and provide fallback implementation if neccessary)
dnl ##
dnl ## configure.in:
dnl ## AC_CHECK_VA_COPY
dnl ## foo.c:
dnl ## #include "config.h"
dnl ## [...]
dnl ## va_copy(d,s)
dnl ##
dnl ## This check is rather complex: first because we really have to
dnl ## try various possible implementations in sequence and second, we
dnl ## cannot define a macro in config.h with parameters directly.
dnl ##
dnl # test program for va_copy() implementation
changequote(<<,>>)
m4_define(__va_copy_test, <<[
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#define DO_VA_COPY(d, s) $1
void test(char *str, ...)
{
va_list ap, ap2;
int i;
va_start(ap, str);
DO_VA_COPY(ap2, ap);
for (i = 1; i <= 9; i++) {
int k = (int)va_arg(ap, int);
if (k != i)
abort();
}
DO_VA_COPY(ap, ap2);
for (i = 1; i <= 9; i++) {
int k = (int)va_arg(ap, int);
if (k != i)
abort();
}
va_end(ap);
}
int main(int argc, char *argv[])
{
test("test", 1, 2, 3, 4, 5, 6, 7, 8, 9);
exit(0);
}
]>>)
changequote([,])
dnl # test driver for va_copy() implementation
m4_define(__va_copy_check, [
AH_VERBATIM($1,
[/* Predefined possible va_copy() implementation (id: $1) */
#define __VA_COPY_USE_$1(d, s) $2])
if test ".$ac_cv_va_copy" = .; then
AC_TRY_RUN(__va_copy_test($2), [ac_cv_va_copy="$1"])
fi
])
dnl # Autoconf check for va_copy() implementation checking
AC_DEFUN([AC_CHECK_VA_COPY],[
dnl # provide Autoconf display check message
AC_MSG_CHECKING(for va_copy() function)
dnl # check for various implementations in priorized sequence
AC_CACHE_VAL(ac_cv_va_copy, [
ac_cv_va_copy=""
dnl # 1. check for standardized C99 macro
__va_copy_check(C99, [va_copy((d), (s))])
dnl # 2. check for alternative/deprecated GCC macro
__va_copy_check(GCM, [VA_COPY((d), (s))])
dnl # 3. check for internal GCC macro (high-level define)
__va_copy_check(GCH, [__va_copy((d), (s))])
dnl # 4. check for internal GCC macro (built-in function)
__va_copy_check(GCB, [__builtin_va_copy((d), (s))])
dnl # 5. check for assignment approach (assuming va_list is a struct)
__va_copy_check(ASS, [do { (d) = (s); } while (0)])
dnl # 6. check for assignment approach (assuming va_list is a pointer)
__va_copy_check(ASP, [do { *(d) = *(s); } while (0)])
dnl # 7. check for memory copying approach (assuming va_list is a struct)
__va_copy_check(CPS, [memcpy((void *)&(d), (void *)&(s)), sizeof((s))])
dnl # 8. check for memory copying approach (assuming va_list is a pointer)
__va_copy_check(CPP, [memcpy((void *)(d), (void *)(s)), sizeof(*(s))])
if test ".$ac_cv_va_copy" = .; then
AC_ERROR([no working implementation found])
fi
])
dnl # optionally activate the fallback implementation
if test ".$ac_cv_va_copy" = ".C99"; then
AC_DEFINE(HAVE_VA_COPY, 1, [Define if va_copy() macro exists (and no fallback implementation is required)])
fi
dnl # declare which fallback implementation to actually use
AC_DEFINE_UNQUOTED([__VA_COPY_USE], [__VA_COPY_USE_$ac_cv_va_copy],
[Define to id of used va_copy() implementation])
dnl # provide activation hook for fallback implementation
AH_VERBATIM([__VA_COPY_ACTIVATION],
[/* Optional va_copy() implementation activation */
#ifndef HAVE_VA_COPY
#define va_copy(d, s) __VA_COPY_USE(d, s)
#endif
])
dnl # provide Autoconf display result message
if test ".$ac_cv_va_copy" = ".C99"; then
AC_MSG_RESULT([yes])
else
AC_MSG_RESULT([no (using fallback implementation)])
fi
])
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