1 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wno-unused %s
2
3 int f(int, int);
4
5 struct A {
6 int x, y;
7 };
8 struct S {
9 S(int, int);
10 };
11
test()12 void test() {
13 int a;
14 int xs[10];
15 ++a = 0; // ok
16 a + ++a; // expected-warning {{unsequenced modification and access to 'a'}}
17 a = ++a; // ok
18 a + a++; // expected-warning {{unsequenced modification and access to 'a'}}
19 a = a++; // expected-warning {{multiple unsequenced modifications to 'a'}}
20 ++ ++a; // ok
21 (a++, a++); // ok
22 ++a + ++a; // expected-warning {{multiple unsequenced modifications to 'a'}}
23 a++ + a++; // expected-warning {{multiple unsequenced modifications}}
24 (a++, a) = 0; // ok, increment is sequenced before value computation of LHS
25 a = xs[++a]; // ok
26 a = xs[a++]; // expected-warning {{multiple unsequenced modifications}}
27 (a ? xs[0] : xs[1]) = ++a; // expected-warning {{unsequenced modification and access}}
28 a = (++a, ++a); // ok
29 a = (a++, ++a); // ok
30 a = (a++, a++); // expected-warning {{multiple unsequenced modifications}}
31 f(a, a); // ok
32 f(a = 0, a); // expected-warning {{unsequenced modification and access}}
33 f(a, a += 0); // expected-warning {{unsequenced modification and access}}
34 f(a = 0, a = 0); // expected-warning {{multiple unsequenced modifications}}
35
36 // Compound assignment "A OP= B" is equivalent to "A = A OP B" except that A
37 // is evaluated only once.
38 (++a, a) = 1; // ok
39 (++a, a) += 1; // ok
40 a = ++a; // ok
41 a += ++a; // expected-warning {{unsequenced modification and access}}
42
43 A agg1 = { a++, a++ }; // ok
44 A agg2 = { a++ + a, a++ }; // expected-warning {{unsequenced modification and access}}
45
46 S str1(a++, a++); // expected-warning {{multiple unsequenced modifications}}
47 S str2 = { a++, a++ }; // ok
48 S str3 = { a++ + a, a++ }; // expected-warning {{unsequenced modification and access}}
49
50 (xs[2] && (a = 0)) + a; // ok
51 (0 && (a = 0)) + a; // ok
52 (1 && (a = 0)) + a; // expected-warning {{unsequenced modification and access}}
53
54 (xs[3] || (a = 0)) + a; // ok
55 (0 || (a = 0)) + a; // expected-warning {{unsequenced modification and access}}
56 (1 || (a = 0)) + a; // ok
57
58 (xs[4] ? a : ++a) + a; // ok
59 (0 ? a : ++a) + a; // expected-warning {{unsequenced modification and access}}
60 (1 ? a : ++a) + a; // ok
61 (xs[5] ? ++a : ++a) + a; // FIXME: warn here
62
63 (++a, xs[6] ? ++a : 0) + a; // expected-warning {{unsequenced modification and access}}
64
65 // Here, the read of the fourth 'a' might happen before or after the write to
66 // the second 'a'.
67 a += (a++, a) + a; // expected-warning {{unsequenced modification and access}}
68
69 int *p = xs;
70 a = *(a++, p); // ok
71 a = a++ && a; // ok
72
73 A *q = &agg1;
74 (q = &agg2)->y = q->x; // expected-warning {{unsequenced modification and access to 'q'}}
75
76 // This has undefined behavior if a == 0; otherwise, the side-effect of the
77 // increment is sequenced before the value computation of 'f(a, a)', which is
78 // sequenced before the value computation of the '&&', which is sequenced
79 // before the assignment. We treat the sequencing in '&&' as being
80 // unconditional.
81 a = a++ && f(a, a);
82
83 // This has undefined behavior if a != 0. FIXME: We should diagnose this.
84 (a && a++) + a;
85
86 (xs[7] && ++a) * (!xs[7] && ++a); // ok
87
88 xs[0] = (a = 1, a); // ok
89 (a -= 128) &= 128; // ok
90 ++a += 1; // ok
91
92 xs[8] ? ++a + a++ : 0; // expected-warning {{multiple unsequenced modifications}}
93 xs[8] ? 0 : ++a + a++; // expected-warning {{multiple unsequenced modifications}}
94 xs[8] ? ++a : a++; // ok
95
96 xs[8] && (++a + a++); // expected-warning {{multiple unsequenced modifications}}
97 xs[8] || (++a + a++); // expected-warning {{multiple unsequenced modifications}}
98
99 (__builtin_classify_type(++a) ? 1 : 0) + ++a; // ok
100 (__builtin_constant_p(++a) ? 1 : 0) + ++a; // ok
101 (__builtin_object_size(&(++a, a), 0) ? 1 : 0) + ++a; // ok
102 (__builtin_expect(++a, 0) ? 1 : 0) + ++a; // expected-warning {{multiple unsequenced modifications}}
103 }
104