#define D1(s, ...) s#define D2(s, ...) s D1(__VA_ARGS__)#define D3(s, ...) s D2(__VA_ARGS__)#define D4(s, ...) s D3(__VA_ARGS__) D1(a)D2(a, b)D3(a, b, c)D4(a, b, c, d) x D4(a, b, c, d) yx D4(a, b, c) yx D4(a, b) yx D4(a) yx D4() y #define GNU_COMMA(X,Y...) X,## Y x GNU_COMMA(A,B,C) yx GNU_COMMA(A,B) yx GNU_COMMA(A) yx GNU_COMMA() y #define __sun_attr___noreturn__ __attribute__((__noreturn__))#define ___sun_attr_inner(__a) __sun_attr_##__a#define __sun_attr__(__a) ___sun_attr_inner __a#define __NORETURN __sun_attr__((__noreturn__))__NORETURN#define X(...)#define Y(...)  1 __VA_ARGS__ 2Y(X X() ())