clang/test/Sema/empty1.c

   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(void) {
  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(void) {
  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 }