1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c11 -Wno-unused %s 2 3 int f(int, int); 4 5 typedef struct A { 6 int x, y; 7 } A; 8 9 void test() { 10 int a; 11 int xs[10]; 12 a + ++a; // expected-warning {{unsequenced modification and access to 'a'}} 13 a = ++a; // expected-warning {{multiple unsequenced modifications to 'a'}} 14 a + a++; // expected-warning {{unsequenced modification and access to 'a'}} 15 a = a++; // expected-warning {{multiple unsequenced modifications to 'a'}} 16 (a++, a++); // ok 17 ++a + ++a; // expected-warning {{multiple unsequenced modifications}} 18 a++ + a++; // expected-warning {{multiple unsequenced modifications}} 19 a = xs[++a]; // expected-warning {{multiple unsequenced modifications}} 20 a = xs[a++]; // expected-warning {{multiple unsequenced modifications}} 21 a = (++a, ++a); // expected-warning {{multiple unsequenced modifications}} 22 a = (a++, ++a); // expected-warning {{multiple unsequenced modifications}} 23 a = (a++, a++); // expected-warning {{multiple unsequenced modifications}} 24 f(a, a); // ok 25 f(a = 0, a); // expected-warning {{unsequenced modification and access}} 26 f(a, a += 0); // expected-warning {{unsequenced modification and access}} 27 f(a = 0, a = 0); // expected-warning {{multiple unsequenced modifications}} 28 a = f(++a, 0); // ok 29 a = f(a++, 0); // ok 30 a = f(++a, a++); // expected-warning {{multiple unsequenced modifications}} 31 32 ++a + f(++a, 0); // expected-warning {{multiple unsequenced modifications}} 33 f(++a, 0) + ++a; // expected-warning {{multiple unsequenced modifications}} 34 a++ + f(a++, 0); // expected-warning {{multiple unsequenced modifications}} 35 f(a++, 0) + a++; // expected-warning {{multiple unsequenced modifications}} 36 37 a = ++a; // expected-warning {{multiple unsequenced modifications}} 38 a += ++a; // expected-warning {{unsequenced modification and access}} 39 40 A agg1 = { a++, a++ }; // expected-warning {{multiple unsequenced modifications}} 41 A agg2 = { a++ + a, a++ }; // expected-warning {{unsequenced modification and access}} 42 43 (xs[2] && (a = 0)) + a; // ok 44 (0 && (a = 0)) + a; // ok 45 (1 && (a = 0)) + a; // expected-warning {{unsequenced modification and access}} 46 47 (xs[3] || (a = 0)) + a; // ok 48 (0 || (a = 0)) + a; // expected-warning {{unsequenced modification and access}} 49 (1 || (a = 0)) + a; // ok 50 51 (xs[4] ? a : ++a) + a; // ok 52 (0 ? a : ++a) + a; // expected-warning {{unsequenced modification and access}} 53 (1 ? a : ++a) + a; // ok 54 (xs[5] ? ++a : ++a) + a; // FIXME: warn here 55 56 (++a, xs[6] ? ++a : 0) + a; // expected-warning {{unsequenced modification and access}} 57 58 // Here, the read of the fourth 'a' might happen before or after the write to 59 // the second 'a'. 60 a += (a++, a) + a; // expected-warning {{unsequenced modification and access}} 61 62 int *p = xs; 63 a = *(a++, p); // ok 64 a = a++ && a; // ok 65 66 A *q = &agg1; 67 (q = &agg2)->y = q->x; // expected-warning {{unsequenced modification and access to 'q'}} 68 69 // This has undefined behavior if a == 0; otherwise, the side-effect of the 70 // increment is sequenced before the value computation of 'f(a, a)', which is 71 // sequenced before the value computation of the '&&', which is sequenced 72 // before the assignment. We treat the sequencing in '&&' as being 73 // unconditional. 74 a = a++ && f(a, a); 75 76 // This has undefined behavior if a != 0. FIXME: We should diagnose this. 77 (a && a++) + a; 78 79 (xs[7] && ++a) * (!xs[7] && ++a); // ok 80 81 xs[0] = (a = 1, a); // ok 82 83 xs[8] ? ++a + a++ : 0; // expected-warning {{multiple unsequenced modifications}} 84 xs[8] ? 0 : ++a + a++; // expected-warning {{multiple unsequenced modifications}} 85 xs[8] ? ++a : a++; // ok 86 87 xs[8] && (++a + a++); // expected-warning {{multiple unsequenced modifications}} 88 xs[8] || (++a + a++); // expected-warning {{multiple unsequenced modifications}} 89 90 (__builtin_classify_type(++a) ? 1 : 0) + ++a; // ok 91 (__builtin_constant_p(++a) ? 1 : 0) + ++a; // ok 92 (__builtin_expect(++a, 0) ? 1 : 0) + ++a; // expected-warning {{multiple unsequenced modifications}} 93 _Generic(++a, default: 0) + ++a; // ok 94 sizeof(++a) + ++a; // ok 95 _Alignof(++a) + ++a; // expected-warning {{extension}} 96 } 97
