Possible bug in cpp

[Jonathan Ryshpan]

I'm trying to build a debugging macro which will emit the file and line number
along with other things I want to print; and am having a little trouble.  I've
located the problem in cpp, but don't know whether it's my fault or a bug.

The difficulty is that in the example below cpp eats __LINE__ when there are
no arguments to PRINTD() macro, but everything works fine if there is at 
least one argument.

Here's the id info for the cpp that I'm running:
======================= Info Starts ======================= 
$ /lib/cpp -v
GNU CPP version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release) (i386 Linux/ELF)
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/i386-redhat-linux/include
 /usr/lib/gcc-lib/i386-redhat-linux/egcs-2.91.66/include
 /usr/include
End of search list.
======================= Info Ends ======================= 


Here are the two input files:

======================= debug.h Starts ======================= 
# define PRINTD(fmt, args...) fprintf(stderr, "%s:%d - " fmt, __FILE__, __LINE__, ## args)
======================= debug.h Ends ======================= 

======================= test-debug.c Starts ======================= 
#include <stdio.h>
#include "debug.h"

main(argc, argv)
{
	printf("This is a test\n");
	PRINTD("Error\n");
	PRINTD("Error-1\n", 1);
	return 0;
}
======================= test-debug.c Ends ======================= 

$ cc -E test-debug.c
produces output ending with:
======================= Output Starts ======================= 
...
# 1 "test-debug.c" 2

# 1 "debug.h" 1

# 2 "test-debug.c" 2

main(argc, argv)
{
	printf("This is a test\n");
	fprintf(stderr, "%s:%d - "  "Error\n" , "test-debug.c",  ) ;
	fprintf(stderr, "%s:%d - "  "Error-1\n" , "test-debug.c", 8,1 ) ;
	return 0;
}
======================= Output Ends =======================