dead-stores.c revision 28433ff063fe5ba5eac486d4bfcfa9e210097772 
1// RUN: clang-cc -analyze -warn-dead-stores -verify %s &&
2// RUN: clang-cc -analyze -checker-simple -analyzer-store=basic -analyzer-constraints=basic -warn-dead-stores -verify %s &&
3// RUN: clang-cc -analyze -checker-simple -analyzer-store=basic -analyzer-constraints=range -warn-dead-stores -verify %s &&
4// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic -analyzer-constraints=basic -warn-dead-stores -verify %s &&
5// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic -analyzer-constraints=range -warn-dead-stores -verify %s &&
6// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=basic -warn-dead-stores -verify %s &&
7// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=range -warn-dead-stores -verify %s
8
9void f1() {
10  int k, y;
11  int abc=1;
12  long idx=abc+3*5; // expected-warning {{never read}}
13}
14
15void f2(void *b) {
16 char *c = (char*)b; // no-warning
17 char *d = b+1; // expected-warning {{never read}}
18 printf("%s", c); // expected-warning{{implicitly declaring C library function 'printf' with type 'int (char const *, ...)'}} \
19 // expected-note{{please include the header <stdio.h> or explicitly provide a declaration for 'printf'}}
20}
21
22void f3() {
23  int r;
24  if ((r = f()) != 0) { // no-warning
25    int y = r; // no-warning
26    printf("the error is: %d\n", y);
27  }
28}
29
30void f4(int k) {
31
32  k = 1;
33
34  if (k)
35    f1();
36
37  k = 2;  // expected-warning {{never read}}
38}
39
40void f5() {
41
42  int x = 4; // no-warning
43  int *p = &x; // expected-warning{{never read}}
44
45}
46
47int f6() {
48
49  int x = 4;
50  ++x; // expected-warning{{never read}}
51  return 1;
52}
53
54int f7(int *p) {
55  // This is allowed for defensive programming.
56  p = 0; // no-warning
57  return 1;
58}
59
60int f8(int *p) {
61  extern int *baz();
62  if (p = baz()) // expected-warning{{Although the value}}
63    return 1;
64  return 0;
65}
66
67int f9() {
68  int x = 4;
69  x = x + 10; // expected-warning{{never read}}
70  return 1;
71}
72
73int f10() {
74  int x = 4;
75  x = 10 + x; // expected-warning{{never read}}
76  return 1;
77}
78
79int f11() {
80  int x = 4;
81  return x++; // expected-warning{{never read}}
82}
83
84int f11b() {
85  int x = 4;
86  return ((((++x)))); // no-warning
87}
88
89int f12a(int y) {
90  int x = y;  // expected-warning{{never read}}
91  return 1;
92}
93int f12b(int y) {
94  int x __attribute__((unused)) = y;  // no-warning
95  return 1;
96}
97
98// Filed with PR 2630.  This code should produce no warnings.
99int f13(void)
100{
101  int a = 1;
102  int b, c = b = a + a;
103
104  if (b > 0)
105    return (0);
106
107  return (a + b + c);
108}
109
110// Filed with PR 2763.
111int f14(int count) {
112  int index, nextLineIndex;
113  for (index = 0; index < count; index = nextLineIndex+1) {
114    nextLineIndex = index+1;  // no-warning
115    continue;
116  }
117  return index;
118}
119
120// Test case for <rdar://problem/6248086>
121void f15(unsigned x, unsigned y) {
122  int count = x * y;   // no-warning
123  int z[count];
124}
125
126int f16(int x) {
127  x = x * 2;
128  x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}}
129      ? 5 : 8;
130  return x;
131}
132
133// Self-assignments should not be flagged as dead stores.
134int f17() {
135  int x = 1;
136  x = x; // no-warning
137}
138
139// <rdar://problem/6506065>
140// The values of dead stores are only "consumed" in an enclosing expression
141// what that value is actually used.  In other words, don't say "Although the value stored to 'x' is used...".
142int f18() {
143   int x = 0; // no-warning
144   if (1)
145      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
146   while (1)
147      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
148   do
149      x = 10;   // expected-warning{{Value stored to 'x' is never read}}
150   while (1);
151
152   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'}}
153}
154
155// PR 3514: false positive `dead initialization` warning for init to global
156//  http://llvm.org/bugs/show_bug.cgi?id=3514
157extern const int MyConstant;
158int f19(void) {
159  int x = MyConstant;  // no-warning
160  x = 1;
161  return x;
162}
163
164int f19b(void) { // This case is the same as f19.
165  const int MyConstant = 0;
166  int x = MyConstant; // no-warning
167  x = 1;
168  return x;
169}
170
171void f20(void) {
172  int x = 1; // no-warning
173#pragma unused(x)
174}
175
176