c/3711: va_arg + var size struct + typeof crash gcc 3.1

Nicola Pero nicola@brainstorm.co.uk
Tue Jul 17 08:36:00 GMT 2001


>Number:         3711
>Category:       c
>Synopsis:       va_arg + var size struct + typeof crash gcc 3.1
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          ice-on-legal-code
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 17 08:36:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Nicola Pero
>Release:        3.1 20010717
>Organization:
>Environment:
gnu
>Description:
Gcc 3.1 seems to have problems with typeof + va_arg 
+ variable size structs; the code shown crashes gcc-3.1;
it works with the other gcc versions I tried, 
which were gcc-3.0 and gcc-2.91.66.
>How-To-Repeat:
Compile the following code:


#include <stdarg.h>
#include <stdio.h>

/* This function really accepts a size, and then a struct. 
   We use variable args only to show a bug in the compiler. */
void functionWithArgs (int size, ...)
{
  struct 
  {
    char        x[size];
  } dummy;
  va_list ap;
  int i;

  va_start (ap, size);
  dummy = va_arg (ap, typeof(dummy));
  for (i = 0; i < size; i++)
    {
      printf ("%c\n", (dummy.x)[i]);
    }
  va_end (ap);
}

int main (void)
{
  struct 
  {
    char y[5];
  } test;
  
  (test.y)[0] = '1';
  (test.y)[1] = '2';
  (test.y)[2] = '3';
  (test.y)[3] = '4';
  (test.y)[4] = '5';

  functionWithArgs (5, test);
  
  return 0;
}
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:



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