Bug in cpp macro varargs extension

[Kaveh R. Ghazi]

	Does anyone use gcc's macro varargs extension?  Is is
considered usable?

	I'm having several problems getting correct expansions.  I think
it boils down to this test case:

 > #define error1(msg, args...) printf(msg, "foo", ## args)
 > #define error2(msg, args...) printf("foo", msg, ## args)
 >  
 > main()
 > {
 >   error1("%s, %s", "hello");
 >   error2("%s, %s", "hello");
 >  
 >   error1("%s");
 >   error2("%s");
 > }

	Running this through either the current egcs snapshot yields:

 > main()
 > {
 >   printf( "%s, %s" , "foo","hello" ) ;
 >   printf("foo",  "%s, %s" ,"hello" ) ;
 >  
 >   printf( "%s" ,  ) ;
 >   printf("foo",  "%s"  ) ;
 > }

	Notice that the 3rd printf is missing an argument.  I believe
that whenever the expansion inserts stuff right before the varargs
that's not a macro parameter, it gets lost.  But this is only true
if args... evaluates to nothing, as can be seen in the first printf.

	Can anyone help with this bug?

		Thanks,
		--Kaveh

PS: This is with cccp.c, I haven't tried cpplib.

--
Kaveh R. Ghazi			Engagement Manager / Project Services
ghazi@caip.rutgers.edu		Qwest Internet Solutions