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d_bltinoffsetof.c revision 1.3 
      1 /*	$NetBSD: d_bltinoffsetof.c,v 1.3 2024/01/09 23:46:54 rillig Exp $	*/
      2 # 3 "d_bltinoffsetof.c"
      3 
      4 struct foo {
      5 	union {
      6 		struct {
      7 			struct {
      8 				int a;
      9 				int b;
     10 			} first;
     11 			char *second;
     12 		} s;
     13 		unsigned char padding[1000];
     14 	} u;
     15 	union {
     16 		int a;
     17 		double b;
     18 	} array[50];
     19 };
     20 
     21 typedef int first[-(int)__builtin_offsetof(struct foo, u.s.first)];
     22 typedef int first_a[-(int)__builtin_offsetof(struct foo, u.s.first.a)];
     23 /* expect+1: ... (-4) ... */
     24 typedef int first_b[-(int)__builtin_offsetof(struct foo, u.s.first.b)];
     25 /* expect+1: ... (-8) ... */
     26 typedef int second[-(int)__builtin_offsetof(struct foo, u.s.second)];
     27 
     28 /* expect+1: ... (-1000) ... */
     29 typedef int array[-(int)__builtin_offsetof(struct foo, array)];
     30 /* expect+1: ... (-1000) ... */
     31 typedef int array_0_a[-(int)__builtin_offsetof(struct foo, array[0].a)];
     32 /* expect+1: ... (-1000) ... */
     33 typedef int array_0_b[-(int)__builtin_offsetof(struct foo, array[0].b)];
     34 /* expect+1: ... (-1008) ... */
     35 typedef int array_1_a[-(int)__builtin_offsetof(struct foo, array[1].a)];
     36 
     37 // There is no element array[50], but pointing right behind the last element
     38 // may be fine.
     39 /* expect+1: ... (-1400) ... */
     40 typedef int array_50_a[-(int)__builtin_offsetof(struct foo, array[50].a)];
     41 /* expect+1: ... (-1400) ... */
     42 typedef int sizeof_foo[-(int)sizeof(struct foo)];
     43 
     44 
     45 // 51 is out of bounds, as it is larger than the size of the struct.
     46 // No warning though, maybe later.
     47 /* expect+1: ... (-1408) ... */
     48 typedef int array_51_a[-(int)__builtin_offsetof(struct foo, array[51].a)];
     49