va_list q

[Marcel Moolenaar]

On Wed, Apr 21, 2004 at 06:51:27PM +0300, Valentin Nechayev wrote:
> 
> cc -O -pipe   -g -I../include -DHAVE_PATHS_H -D_BITYPES  -c utils.c
> utils.c: In function `vslprintf':
> utils.c:253: error: invalid use of non-lvalue array
> *** Error code 1
> 
> The code in question is:
> 
> int
> vslprintf(buf, buflen, fmt, args)
> [...]
> #ifndef __powerpc__
> >            n = vslprintf(buf, buflen + 1, f, va_arg(args, va_list));
> #else
>             /* On the powerpc, a va_list is an array of 1 structure */
>             n = vslprintf(buf, buflen + 1, f, va_arg(args, void *));
> #endif
> 
> (I selected failed line with '>')
> 
> va_arg() uses translation to pointer to specified type; this translation
> fails with message shown above. Can anybody say how can it be fixed,
> and whether shown powerpc hack is applicable to ia64 if it's good solution?

The use of va_arg(args, va_list) works on ia64 (FreeBSD, HP-UX and Linux).
Given the limited context, I can only suggest that you try to create a
temporary variable of type va_list and change the offending line to:

	va_list tmpvalist = va_arg(args, va_list);
	n = vslprintf(buf, buflen + 1, f, tmpvalist);

This may make the compiler happy by giving it more type awareness.
Attached a simple testcase that va_arg(ap, va_list) works.

-- 
 Marcel Moolenaar	  USPA: A-39004		 marcel at xcllnt.net
-------------- next part --------------
#include <stdarg.h>
#include <stdio.h>

int
vf2(int count, va_list ap)
{
	va_list val;
	int i, n;

	printf("%d ->", count);

	val = va_arg(ap, va_list);
	for (i = 0; i < count; i++) {
		n = va_arg(val, int);
		printf(" %d", n);
	}
	printf("\n");
	return (0);
}

int
f2(int count, ...)
{
	va_list ap;
	int ret;

	va_start(ap, count);
	ret = vf2(count, ap);
	va_end(ap);
	return (ret);
}

int
vf1(int count, va_list ap)
{
	return (f2(count, ap));
}

int
f1(int count, ...)
{
	va_list ap;
	int ret;

	va_start(ap, count);
	ret = vf1(count, ap);
	va_end(ap);
	return (ret);
}

int
main()
{
	return (f1(3, 1, 2, 3));
}