c compiler: Problems with constants

gcc will compile the folowing code, but cscc produces errors for the last two 
statements:

test.c:8: constant value required
test.c:9: constant value required

main () {
	/* sizeof void * and long appear to be compile-time constants */
	{
		char c [sizeof (long)];
		char d [sizeof (void *)];
	}
	/* but not if you add one... */
	{
		char c [sizeof (long) + 1];
		char d [sizeof (void *) + 1];
	}
	/* but addition of literal constants doesn't cause problems... */
	{
		char c [8 + 1];
		char d [4 + 1];
	}
}

I also discovered that the following compiles on gcc but not cscc (syntax 
error, unexpected 'int').  I don't know how important this is:

main ()
{
        int i;
        {
                /* do nothing*/
        }
        int j;
}

I guess this is because cscc assumes that something apart from variable 
declarations happens inside the subblock - which excludes futher variable 
declarations i.e. the declaration of j - at the parsing level.  Presumably 
gcc leaves this check until later when it can see that the subblock contains 
nothing that is not a variable declaration inside.

Thanks in advance

Alan Jenkins