Insufficient support for va_list type

[arkt8]

Describe the bug

There is no documented va_list alternative for use when using C bindings, but looks like there is a partial support when using v translate.

Reproduction Steps

File test.c:

#include <stdarg.h>

int sum(int qtd, ...) {
  va_list va;
  int s = 0;
  va_start(va, qtd);
  for (int i=0; i < qtd; i++) {
    s += (va_arg(va, int));
  }
  va_end(va);
  return s;
}

int main() {
  printf("Result %d\n", sum(3,4,5,6));
  return 0;
}

Then run:
v translate test.c

Expected Behavior

Work seamlessly converting to V and, after running the resulting binary print on screen:
Result 15

Current Behavior

The command v translate test.c gives the following error:

C to V translator 0.4.0
  translating /tmp/test.c     ... test.v:10:9: error: invalid expression: unexpected token `)`
    8 |     __builtin_va_start(va, qtd)
    9 |     for i := 0 ; i < qtd ; i ++ {
   10 |         s += ()
      |               ^
   11 |     }
   12 |     __builtin_va_end(va)

Internal vfmt error while formatting file: /tmp/test.v.
Encountered a total of: 1 errors.
 took    35 ms ; output .v file: test.v
Translated   1 files in    35 ms.

Possible Solution

Partial / insufficient implementation of va_list or stdarg.h.

Additional Information/Context

Even with the error, V still generates a test.v file with the following content:

@[translated]
module main

@[c2v_variadic]
fn sum(qtd int) int {
	va := Va_list{}
	mas := 0
	__builtin_va_start(va, qtd)
	for i := 0 ; i < qtd ; i ++ {
		s += ()
	}
	__builtin_va_end(va)
	return s
}

fn main()  {
	C.printf(c'Result %d\n', sum(3, 4, 5, 6))
	return 
}

V version

0.4.4 0205154

Environment details (OS name and version, etc.)

v doctor output:

V full version: V 0.4.4 65a1d2f.0205154
OS: linux, Debian GNU/Linux bookworm/sid
Processor: 4 cpus, 64bit, little endian, Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz

getwd: /tmp
vexe: /opt/v/v
vexe mtime: 2024-01-23 01:53:07

vroot: OK, value: /opt/v
VMODULES: OK, value: /home/thadeu/.vmodules
VTMP: OK, value: /tmp/v_101000

Git version: git version 2.34.1
Git vroot status: weekly.2024.03-53-g02051540
.git/config present: true

CC version: cc (Debian 12.2.0-14) 12.2.0
thirdparty/tcc status: thirdparty-linux-amd64 12f392c3-dirty

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