dead-stores.c revision d427023c334fe03105d9359711a3df4d6f23b344 
1// RUN: clang -analyze -warn-dead-stores -verify %s &&
2// RUN: clang -analyze -checker-simple -warn-dead-stores -verify %s &&
3// RUN: clang -analyze -warn-dead-stores -checker-simple -verify %s
4
5
6void f1() {
7  int k, y;
8  int abc=1;
9  long idx=abc+3*5; // expected-warning {{never read}}
10}
11
12void f2(void *b) {
13 char *c = (char*)b; // no-warning
14 char *d = b+1; // expected-warning {{never read}}
15 printf("%s", c);
16}
17
18void f3() {
19  int r;
20  if ((r = f()) != 0) { // no-warning
21    int y = r; // no-warning
22    printf("the error is: %d\n", y);
23  }
24}
25
26void f4(int k) {
27
28  k = 1;
29
30  if (k)
31    f1();
32
33  k = 2;  // expected-warning {{never read}}
34}
35
36void f5() {
37
38  int x = 4; // no-warning
39  int *p = &x; // expected-warning{{never read}}
40
41}
42
43int f6() {
44
45  int x = 4;
46  ++x; // expected-warning{{never read}}
47  return 1;
48}
49
50int f7(int *p) {
51  // This is allowed for defensive programming.
52  p = 0; // no-warning
53  return 1;
54}
55
56int f8(int *p) {
57  extern int *baz();
58  if (p = baz()) // expected-warning{{Although the value}}
59    return 1;
60  return 0;
61}
62
63int f9() {
64  int x = 4;
65  x = x + 10; // expected-warning{{never read}}
66  return 1;
67}
68
69int f10() {
70  int x = 4;
71  x = 10 + x; // expected-warning{{never read}}
72  return 1;
73}
74
75int f11() {
76  int x = 4;
77  return x++; // expected-warning{{never read}}
78}
79
80int f11b() {
81  int x = 4;
82  return ((((++x)))); // no-warning
83}
84
85int f12a(int y) {
86  int x = y;  // expected-warning{{never read}}
87  return 1;
88}
89int f12b(int y) {
90  int x __attribute__((unused)) = y;  // no-warning
91  return 1;
92}
93
94// Filed with PR 2630.  This code should produce no warnings.
95int f13(void)
96{
97  int a = 1;
98  int b, c = b = a + a;
99
100  if (b > 0)
101    return (0);
102
103  return (a + b + c);
104}
105
106// Filed with PR 2763.
107int f14(int count) {
108  int index, nextLineIndex;
109  for (index = 0; index < count; index = nextLineIndex+1) {
110    nextLineIndex = index+1;  // no-warning
111    continue;
112  }
113  return index;
114}
115
116// Test case for <rdar://problem/6248086>
117void f15(unsigned x, unsigned y) {
118  int count = x * y;   // no-warning
119  int z[count];
120}
121
122int f16(int x) {
123  x = x * 2;
124  x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}}
125      ? 5 : 8;
126  return x;
127}
128
129// Self-assignments should not be flagged as dead stores.
130int f17() {
131  int x = 1;
132  x = x; // no-warning
133}
134
135// <rdar://problem/6506065>
136// The values of dead stores are only "consumed" in an enclosing expression
137// what that value is actually used.  In other words, don't say "Although the value stored to 'x' is used...".
138int f18() {
139   int x = 0; // no-warning
140   if (1)
141      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
142   while (1)
143      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
144   do
145      x = 10;   // expected-warning{{Value stored to 'x' is never read}}
146   while (1);
147
148   return (x = 10); // expected-warning{{Although the value stored to 'x' is used in the enclosing expression, the value is never actually read from 'x'}}
149}
150