empty1.c revision 812d6bcbd13190e6e5c2c915bf1499038d56b44b 
1// RUN: %clang_cc1 %s -fsyntax-only -verify -Wc++-compat
2
3struct emp_1 { // expected-warning {{empty struct has size 0 in C, size 1 in C++}}
4};
5
6union emp_2 { // expected-warning {{empty union has size 0 in C, size 1 in C++}}
7};
8
9struct emp_3 { // expected-warning {{struct has size 0 in C, size 1 in C++}}
10  int : 0;
11};
12
13union emp_4 { // expected-warning {{union has size 0 in C, size 1 in C++}}
14  int : 0;
15};
16
17struct emp_5 { // expected-warning {{struct has size 0 in C, size 1 in C++}}
18  int : 0;
19  int : 0;
20};
21
22union emp_6 { // expected-warning {{union has size 0 in C, size 1 in C++}}
23  int : 0;
24  int : 0;
25};
26
27struct emp_7 { // expected-warning {{struct has size 0 in C, size 1 in C++}}
28  struct emp_1 f1;
29};
30
31union emp_8 { // expected-warning {{union has size 0 in C, size 1 in C++}}
32  struct emp_1 f1;
33};
34
35struct emp_9 { // expected-warning {{struct has size 0 in C, non-zero size in C++}}
36  struct emp_1 f1;
37  union emp_2 f2;
38};
39
40// Checks for pointer subtraction (PR15683)
41struct emp_1 *func_1p(struct emp_1 *x) { return x - 5; }
42
43int func_1() {
44  struct emp_1 v[1];
45  return v - v; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}}
46}
47
48int func_2(struct emp_1 *x) {
49  return 1 + x - x; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}}
50}
51
52int func_3(struct emp_1 *x, struct emp_1 *y) {
53  return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}}
54}
55
56int func_4(struct emp_1 *x, const struct emp_1 *y) {
57  return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}}
58}
59
60int func_5(volatile struct emp_1 *x, const struct emp_1 *y) {
61  return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}}
62}
63
64int func_6() {
65  union emp_2 v[1];
66  return v - v; // expected-warning {{subtraction of pointers to type 'union emp_2' of zero size has undefined behavior}}
67}
68
69struct A; // expected-note {{forward declaration of 'struct A'}}
70
71int func_7(struct A *x, struct A *y) {
72  return x - y; // expected-error {{arithmetic on a pointer to an incomplete type 'struct A'}}
73}
74
75int func_8(struct emp_1 (*x)[10], struct emp_1 (*y)[10]) {
76  return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1 [10]' of zero size has undefined behavior}}
77}
78
79int func_9(struct emp_1 (*x)[], struct emp_1 (*y)[]) {
80  return x - y; // expected-error {{arithmetic on a pointer to an incomplete type 'struct emp_1 []'}}
81}
82
83int func_10(int (*x)[0], int (*y)[0]) {
84  return x - y; // expected-warning {{subtraction of pointers to type 'int [0]' of zero size has undefined behavior}}
85}
86