107 lines · c
1// RUN: %clang_cc1 -fsyntax-only -verify -std=c11 -Wno-unused %s2 3int f(int, int);4 5typedef struct A {6 int x, y;7} A;8 9void test(void) {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++); // ok17 ++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); // ok25 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); // ok29 a = f(a++, 0); // ok30 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; // expected-warning {{unsequenced modification and access to 'a'}}44 (0 && (a = 0)) + a; // ok45 (1 && (a = 0)) + a; // expected-warning {{unsequenced modification and access}}46 47 (xs[3] || (a = 0)) + a; // expected-warning {{unsequenced modification and access to 'a'}}48 (0 || (a = 0)) + a; // expected-warning {{unsequenced modification and access}}49 (1 || (a = 0)) + a; // ok50 51 (xs[4] ? a : ++a) + a; // expected-warning {{unsequenced modification and access to 'a'}}52 (0 ? a : ++a) + a; // expected-warning {{unsequenced modification and access}}53 (1 ? a : ++a) + a; // ok54 (xs[5] ? ++a : ++a) + a; // expected-warning {{unsequenced modification and access to 'a'}}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 to59 // the second 'a'.60 a += (a++, a) + a; // expected-warning {{unsequenced modification and access}}61 62 int *p = xs;63 a = *(a++, p); // ok64 a = a++ && a; // ok65 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 the70 // increment is sequenced before the value computation of 'f(a, a)', which is71 // sequenced before the value computation of the '&&', which is sequenced72 // before the assignment. We treat the sequencing in '&&' as being73 // unconditional.74 a = a++ && f(a, a);75 76 // This has undefined behavior if a != 0.77 (a && a++) + a; // expected-warning {{unsequenced modification and access to 'a'}}78 79 // FIXME: Find a way to avoid warning here.80 (xs[7] && ++a) * (!xs[7] && ++a); // expected-warning {{multiple unsequenced modifications to 'a'}}81 82 xs[0] = (a = 1, a); // ok83 84 xs[8] ? ++a + a++ : 0; // expected-warning {{multiple unsequenced modifications}}85 xs[8] ? 0 : ++a + a++; // expected-warning {{multiple unsequenced modifications}}86 xs[8] ? ++a : a++; // ok87 88 xs[8] && (++a + a++); // expected-warning {{multiple unsequenced modifications}}89 xs[8] || (++a + a++); // expected-warning {{multiple unsequenced modifications}}90 91 (__builtin_classify_type(++a) ? 1 : 0) + ++a; // ok92 (__builtin_constant_p(++a) ? 1 : 0) + ++a; // ok93 (__builtin_expect(++a, 0) ? 1 : 0) + ++a; // expected-warning {{multiple unsequenced modifications}}94 _Generic(++a, default: 0) + ++a; // ok95 sizeof(++a) + ++a; // ok96 _Alignof(++a) + ++a; // expected-warning {{extension}}97 98 __builtin_constant_p(f(++a, 0)) ? f(f(++a, 0), f(++a, 0)) : 0;99 100 if (0) ++a + ++a; // ok, unreachable101}102 103void g(const char *p, int n) {104 // This resembles code produced by some macros in glibc's <string.h>.105 __builtin_constant_p(p) && __builtin_constant_p(++n) && (++n + ++n);106}107