88 lines · c
1// RUN: %clang_cc1 %s -triple %itanium_abi_triple -fsyntax-only -verify -Wc++-compat2 3// Note: Empty C structs are 4 bytes in the Microsoft ABI.4 5struct emp_1 { // expected-warning {{empty struct has size 0 in C, size 1 in C++}}6};7 8union emp_2 { // expected-warning {{empty union has size 0 in C, size 1 in C++}}9};10 11struct emp_3 { // expected-warning {{struct has size 0 in C, size 1 in C++}}12 int : 0;13};14 15union emp_4 { // expected-warning {{union has size 0 in C, size 1 in C++}}16 int : 0;17};18 19struct emp_5 { // expected-warning {{struct has size 0 in C, size 1 in C++}}20 int : 0;21 int : 0;22};23 24union emp_6 { // expected-warning {{union has size 0 in C, size 1 in C++}}25 int : 0;26 int : 0;27};28 29struct emp_7 { // expected-warning {{struct has size 0 in C, size 1 in C++}}30 struct emp_1 f1;31};32 33union emp_8 { // expected-warning {{union has size 0 in C, size 1 in C++}}34 struct emp_1 f1;35};36 37struct 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)43struct emp_1 *func_1p(struct emp_1 *x) { return x - 5; }44 45int 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 50int 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 54int 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 58int 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 62int 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 66int 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 71struct A; // expected-note {{forward declaration of 'struct A'}}72 73int 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 77int 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 81int 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 85int 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