Problems with va_start on X86_64

[joukj]

I get the following with VSI C X7.4-726 (GEM 50x23) on OpenVMS x86_64 E9.2-1

$ ty test.c
#include <varargs.h>
main()
{
va_list ap;
va_start( ap );
}
1-MAY-2023 10:33:59
$ cc test.c

va_start( ap );
...^
%CC-E-UNDECLARED, In this statement, "va_alist" is not declared.
at line number 5 in file $DISK0:[JOUKJ.test]TEST.C;4


A bug or do I mjss something?

Jouk

[jonesd]

I get the following with VSI C X7.4-726 (GEM 50x23) on OpenVMS x86_64 E9.2-1

$ ty test.c
#include <varargs.h>

The release notes in sys$help reccommend (strongly suggest) you convert to using <stdarg.h> instead of <varargs.h>.

[arne_v]

varargs.h should either work or give a "not supported anymore" type of error.

But stdarg.h has been the standard since C89 (34 years), so recommending it certainly makes sense.

[joukj]

However "help crtl va_start" gives varargs.h as header.
Changing to stdarg.h seems to help me.

thanks
Jouk

[arne_v]

I get the exact same error on VMS Alpha with that code.

$ typ z.c
#include <varargs.h>

int main()
{
va_list ap;
va_start( ap );
return 0;
}
$ cc z

va_start( ap );
....^
%CC-E-UNDECLARED, In this statement, "va_alist" is not declared.
at line number 6 in file DISK2:[ARNE]z.c;5

Added in 11 minutes 15 seconds:
There seems to be certain differences between varargs.h and stdarg.h usage:

Code: Select all

$ type va1.c
#include <stdio.h>
#include <stdarg.h>

void test(int n, ...)
{
    int i;
    va_list ap;
    va_start(ap, n);
    for(i = 0; i < n; i++)
    {
       printf("%d : %s\n", i, va_arg(ap, char *));
    }
    va_end(ap);
}

int main(int argc, char *argv[])
{
    test(1, "A");
    test(2, "A", "BB");
    test(3, "A", "BB", "CCC");
    return 0;
}
$ cc va1
$ link va1
$ run va1
0 : A
0 : A
1 : BB
0 : A
1 : BB
2 : CCC
$ type va2.c
#include <stdio.h>
#include <varargs.h>

void test(n, va_alist)
int n;
va_dcl
{
    int i;
    va_list ap;
    va_start(ap);
    for(i = 0; i < n; i++)
    {
       printf("%d : %s\n", i, va_arg(ap, char *));
    }
    va_end(ap);
}

int main(int argc, char *argv[])
{
    test(1, "A");
    test(2, "A", "BB");
    test(3, "A", "BB", "CCC");
    return 0;
}
$ cc va2
$ link va2
$ run va2
0 : A
0 : A
1 : BB
0 : A
1 : BB
2 : CCC