dead-stores.c revision a316e7b735b12ce6b34961a9dcfaae34f4b08d29 
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); // expected-warning{{implicitly declaring C library function 'printf' with type 'int (char const *, ...)'}} \
16 // expected-note{{please include the header <stdio.h> or explicitly provide a declaration for 'printf'}}
17}
18
19void f3() {
20  int r;
21  if ((r = f()) != 0) { // no-warning
22    int y = r; // no-warning
23    printf("the error is: %d\n", y);
24  }
25}
26
27void f4(int k) {
28
29  k = 1;
30
31  if (k)
32    f1();
33
34  k = 2;  // expected-warning {{never read}}
35}
36
37void f5() {
38
39  int x = 4; // no-warning
40  int *p = &x; // expected-warning{{never read}}
41
42}
43
44int f6() {
45
46  int x = 4;
47  ++x; // expected-warning{{never read}}
48  return 1;
49}
50
51int f7(int *p) {
52  // This is allowed for defensive programming.
53  p = 0; // no-warning
54  return 1;
55}
56
57int f8(int *p) {
58  extern int *baz();
59  if (p = baz()) // expected-warning{{Although the value}}
60    return 1;
61  return 0;
62}
63
64int f9() {
65  int x = 4;
66  x = x + 10; // expected-warning{{never read}}
67  return 1;
68}
69
70int f10() {
71  int x = 4;
72  x = 10 + x; // expected-warning{{never read}}
73  return 1;
74}
75
76int f11() {
77  int x = 4;
78  return x++; // expected-warning{{never read}}
79}
80
81int f11b() {
82  int x = 4;
83  return ((((++x)))); // no-warning
84}
85
86int f12a(int y) {
87  int x = y;  // expected-warning{{never read}}
88  return 1;
89}
90int f12b(int y) {
91  int x __attribute__((unused)) = y;  // no-warning
92  return 1;
93}
94
95// Filed with PR 2630.  This code should produce no warnings.
96int f13(void)
97{
98  int a = 1;
99  int b, c = b = a + a;
100
101  if (b > 0)
102    return (0);
103
104  return (a + b + c);
105}
106
107// Filed with PR 2763.
108int f14(int count) {
109  int index, nextLineIndex;
110  for (index = 0; index < count; index = nextLineIndex+1) {
111    nextLineIndex = index+1;  // no-warning
112    continue;
113  }
114  return index;
115}
116
117// Test case for <rdar://problem/6248086>
118void f15(unsigned x, unsigned y) {
119  int count = x * y;   // no-warning
120  int z[count];
121}
122
123int f16(int x) {
124  x = x * 2;
125  x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}}
126      ? 5 : 8;
127  return x;
128}
129
130// Self-assignments should not be flagged as dead stores.
131int f17() {
132  int x = 1;
133  x = x; // no-warning
134}
135
136// <rdar://problem/6506065>
137// The values of dead stores are only "consumed" in an enclosing expression
138// what that value is actually used.  In other words, don't say "Although the value stored to 'x' is used...".
139int f18() {
140   int x = 0; // no-warning
141   if (1)
142      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
143   while (1)
144      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
145   do
146      x = 10;   // expected-warning{{Value stored to 'x' is never read}}
147   while (1);
148
149   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'}}
150}
151
152// PR 3514: false positive `dead initialization` warning for init to global
153//  http://llvm.org/bugs/show_bug.cgi?id=3514
154extern const int MyConstant;
155int f19(void) {
156  int x = MyConstant;  // no-warning
157  x = 1;
158  return x;
159}
160
161int f19b(void) { // FIXME: Should this case be considered the same as f19?
162  const int MyConstant = 0;
163  int x = MyConstant; // expected-warning{{never read}}
164  x = 1;
165  return x;
166}
167