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150
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1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c11 -Wno-unused %s
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2
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3 int f(int, int);
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4
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5 typedef struct A {
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6 int x, y;
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7 } A;
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8
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9 void test() {
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10 int a;
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11 int xs[10];
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12 a + ++a; // expected-warning {{unsequenced modification and access to 'a'}}
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13 a = ++a; // expected-warning {{multiple unsequenced modifications to 'a'}}
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14 a + a++; // expected-warning {{unsequenced modification and access to 'a'}}
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15 a = a++; // expected-warning {{multiple unsequenced modifications to 'a'}}
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16 (a++, a++); // ok
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17 ++a + ++a; // expected-warning {{multiple unsequenced modifications}}
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18 a++ + a++; // expected-warning {{multiple unsequenced modifications}}
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19 a = xs[++a]; // expected-warning {{multiple unsequenced modifications}}
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20 a = xs[a++]; // expected-warning {{multiple unsequenced modifications}}
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21 a = (++a, ++a); // expected-warning {{multiple unsequenced modifications}}
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22 a = (a++, ++a); // expected-warning {{multiple unsequenced modifications}}
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23 a = (a++, a++); // expected-warning {{multiple unsequenced modifications}}
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24 f(a, a); // ok
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25 f(a = 0, a); // expected-warning {{unsequenced modification and access}}
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26 f(a, a += 0); // expected-warning {{unsequenced modification and access}}
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27 f(a = 0, a = 0); // expected-warning {{multiple unsequenced modifications}}
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28 a = f(++a, 0); // ok
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29 a = f(a++, 0); // ok
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30 a = f(++a, a++); // expected-warning {{multiple unsequenced modifications}}
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31
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32 ++a + f(++a, 0); // expected-warning {{multiple unsequenced modifications}}
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33 f(++a, 0) + ++a; // expected-warning {{multiple unsequenced modifications}}
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34 a++ + f(a++, 0); // expected-warning {{multiple unsequenced modifications}}
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35 f(a++, 0) + a++; // expected-warning {{multiple unsequenced modifications}}
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36
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37 a = ++a; // expected-warning {{multiple unsequenced modifications}}
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38 a += ++a; // expected-warning {{unsequenced modification and access}}
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39
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40 A agg1 = { a++, a++ }; // expected-warning {{multiple unsequenced modifications}}
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41 A agg2 = { a++ + a, a++ }; // expected-warning {{unsequenced modification and access}}
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42
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43 (xs[2] && (a = 0)) + a; // expected-warning {{unsequenced modification and access to 'a'}}
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44 (0 && (a = 0)) + a; // ok
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45 (1 && (a = 0)) + a; // expected-warning {{unsequenced modification and access}}
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46
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47 (xs[3] || (a = 0)) + a; // expected-warning {{unsequenced modification and access to 'a'}}
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48 (0 || (a = 0)) + a; // expected-warning {{unsequenced modification and access}}
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49 (1 || (a = 0)) + a; // ok
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50
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51 (xs[4] ? a : ++a) + a; // expected-warning {{unsequenced modification and access to 'a'}}
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52 (0 ? a : ++a) + a; // expected-warning {{unsequenced modification and access}}
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53 (1 ? a : ++a) + a; // ok
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54 (xs[5] ? ++a : ++a) + a; // expected-warning {{unsequenced modification and access to 'a'}}
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55
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56 (++a, xs[6] ? ++a : 0) + a; // expected-warning {{unsequenced modification and access}}
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57
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58 // Here, the read of the fourth 'a' might happen before or after the write to
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59 // the second 'a'.
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60 a += (a++, a) + a; // expected-warning {{unsequenced modification and access}}
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61
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62 int *p = xs;
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63 a = *(a++, p); // ok
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64 a = a++ && a; // ok
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65
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66 A *q = &agg1;
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67 (q = &agg2)->y = q->x; // expected-warning {{unsequenced modification and access to 'q'}}
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68
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69 // This has undefined behavior if a == 0; otherwise, the side-effect of the
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70 // increment is sequenced before the value computation of 'f(a, a)', which is
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71 // sequenced before the value computation of the '&&', which is sequenced
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72 // before the assignment. We treat the sequencing in '&&' as being
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73 // unconditional.
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74 a = a++ && f(a, a);
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75
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76 // This has undefined behavior if a != 0.
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77 (a && a++) + a; // expected-warning {{unsequenced modification and access to 'a'}}
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78
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79 // FIXME: Find a way to avoid warning here.
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80 (xs[7] && ++a) * (!xs[7] && ++a); // expected-warning {{multiple unsequenced modifications to 'a'}}
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81
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82 xs[0] = (a = 1, a); // ok
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83
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84 xs[8] ? ++a + a++ : 0; // expected-warning {{multiple unsequenced modifications}}
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85 xs[8] ? 0 : ++a + a++; // expected-warning {{multiple unsequenced modifications}}
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86 xs[8] ? ++a : a++; // ok
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87
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88 xs[8] && (++a + a++); // expected-warning {{multiple unsequenced modifications}}
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89 xs[8] || (++a + a++); // expected-warning {{multiple unsequenced modifications}}
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90
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91 (__builtin_classify_type(++a) ? 1 : 0) + ++a; // ok
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92 (__builtin_constant_p(++a) ? 1 : 0) + ++a; // ok
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93 (__builtin_expect(++a, 0) ? 1 : 0) + ++a; // expected-warning {{multiple unsequenced modifications}}
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94 _Generic(++a, default: 0) + ++a; // ok
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95 sizeof(++a) + ++a; // ok
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96 _Alignof(++a) + ++a; // expected-warning {{extension}}
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97
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98 __builtin_constant_p(f(++a, 0)) ? f(f(++a, 0), f(++a, 0)) : 0;
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99
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100 if (0) ++a + ++a; // ok, unreachable
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101 }
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102
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103 void g(const char *p, int n) {
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104 // This resembles code produced by some macros in glibc's <string.h>.
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105 __builtin_constant_p(p) && __builtin_constant_p(++n) && (++n + ++n);
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106 }
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