🚀 go-pugleaf

Is there a good reason why CC expands sizeof itself?  E.g. in

test.c:				test..c:
    struct x {			    struct x { /* sizeof = 8 */
	int a;			    int _x_a ;
	float b;		    float _x_b ;
    };				    } ;

    int foo(struct x y)		    int foo (_auto_y )struct x _auto_y ;
    {				    {
	return y.a + sizeof(y);	    return (_auto_y . _x_a + 8);
    }				    }

why does the  sizeof(y)  become  8  and not  sizeof(struct x)?
Is there some other use CC makes of the size that makes up for the
resulting lack of portability?
-- 
David Eppstein, eppstein@cs.columbia.edu, seismo!columbia!cs!eppstein