1 // RUN: %clang_cc1 %s -triple %itanium_abi_triple -fsyntax-only -verify -Wc++-compat 2 3 // Note: Empty C structs are 4 bytes in the Microsoft ABI. 4 5 struct emp_1 { // expected-warning {{empty struct has size 0 in C, size 1 in C++}} 6 }; 7 8 union emp_2 { // expected-warning {{empty union has size 0 in C, size 1 in C++}} 9 }; 10 11 struct emp_3 { // expected-warning {{struct has size 0 in C, size 1 in C++}} 12 int : 0; 13 }; 14 15 union emp_4 { // expected-warning {{union has size 0 in C, size 1 in C++}} 16 int : 0; 17 }; 18 19 struct emp_5 { // expected-warning {{struct has size 0 in C, size 1 in C++}} 20 int : 0; 21 int : 0; 22 }; 23 24 union emp_6 { // expected-warning {{union has size 0 in C, size 1 in C++}} 25 int : 0; 26 int : 0; 27 }; 28 29 struct emp_7 { // expected-warning {{struct has size 0 in C, size 1 in C++}} 30 struct emp_1 f1; 31 }; 32 33 union emp_8 { // expected-warning {{union has size 0 in C, size 1 in C++}} 34 struct emp_1 f1; 35 }; 36 37 struct emp_9 { // expected-warning {{struct has size 0 in C, non-zero size in C++}} 38 struct emp_1 f1; 39 union emp_2 f2; 40 }; 41 42 // Checks for pointer subtraction (PR15683) 43 struct emp_1 *func_1p(struct emp_1 *x) { return x - 5; } 44 45 int func_1() { 46 struct emp_1 v[1]; 47 return v - v; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}} 48 } 49 50 int func_2(struct emp_1 *x) { 51 return 1 + x - x; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}} 52 } 53 54 int func_3(struct emp_1 *x, struct emp_1 *y) { 55 return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}} 56 } 57 58 int func_4(struct emp_1 *x, const struct emp_1 *y) { 59 return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}} 60 } 61 62 int func_5(volatile struct emp_1 *x, const struct emp_1 *y) { 63 return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1' of zero size has undefined behavior}} 64 } 65 66 int func_6() { 67 union emp_2 v[1]; 68 return v - v; // expected-warning {{subtraction of pointers to type 'union emp_2' of zero size has undefined behavior}} 69 } 70 71 struct A; // expected-note {{forward declaration of 'struct A'}} 72 73 int func_7(struct A *x, struct A *y) { 74 return x - y; // expected-error {{arithmetic on a pointer to an incomplete type 'struct A'}} 75 } 76 77 int func_8(struct emp_1 (*x)[10], struct emp_1 (*y)[10]) { 78 return x - y; // expected-warning {{subtraction of pointers to type 'struct emp_1 [10]' of zero size has undefined behavior}} 79 } 80 81 int func_9(struct emp_1 (*x)[], struct emp_1 (*y)[]) { 82 return x - y; // expected-error {{arithmetic on a pointer to an incomplete type 'struct emp_1 []'}} 83 } 84 85 int func_10(int (*x)[0], int (*y)[0]) { 86 return x - y; // expected-warning {{subtraction of pointers to type 'int [0]' of zero size has undefined behavior}} 87 } 88
