is_na and gcc

[Sundar Dorai-Raj <sundar.dorai-raj@pdf.com>]

Hi all,
  I'm unable to use the is_na macro when compiling with gcc and I'm 
wondering whether this is an S-PLUS issue or a gcc issue?
Below is an example (from the Programmer's guide):

// my_sum.c with an additional line added
#include "S.h"
void my_sum(double *x, long *n, double *sum) {
  long i;
  *sum = 0 ;
  for (i = 0 ; i < *n ; i++) {
    if (is_na(&x[i], S_MODE_DOUBLE)) {
      na_set(sum, S_MODE_DOUBLE);
      break;
    }
    else
      *sum += x[i];
    printf("i = %d; sum = %2.1f\n", i, *sum);
  }
}

$ # compiling using gcc 3.2
$ gcc -c -IC:/Progra~1/Insightful/splus61/include my_sum.c
$ gcc -shared -o S.dll my_sum.o 
-LC:/Progra~1/Insightful/splus61/lib/mingw -lSqpe
> # in S-PLUS
> my.sum <- function(x) .C("my_sum", as.double(x),
+                          as.integer(length(x)),
+                          double(1), NAOK = T)[[3]]
> my.sum(4:10)
i = 0; sum = 4.0
i = 4; sum = 12.0

Process S+6 exited abnormally with code 5 at Wed Jun 18 09:37:35 2003

It appears as if `i' is being changed in the is_na macro. Removing the 
is_na check in my_sum.c produces the correct result (i.e. sum = 49). 
This example works fine when compiling with VC++ 6.0. The gcc compiler 
I'm using is part of the MinGW distribution (gcc 3.2).
I'm using S-PLUS 6.1 in Win2000.

Regards,
Sundar