dead-stores.c revision 6c07bdba93b095b66e2c8c82dd5ed458fa8285ea 
1// RUN: clang-cc -analyze -warn-dead-stores -verify %s &&
2// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic -analyzer-constraints=basic -warn-dead-stores -verify %s &&
3// RUN: clang-cc -analyze -checker-cfref -analyzer-store=basic -analyzer-constraints=range -warn-dead-stores -verify %s &&
4// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=basic -warn-dead-stores -verify %s &&
5// RUN: clang-cc -analyze -checker-cfref -analyzer-store=region -analyzer-constraints=range -warn-dead-stores -verify %s
6
7void f1() {
8  int k, y;
9  int abc=1;
10  long idx=abc+3*5; // expected-warning {{never read}}
11}
12
13void f2(void *b) {
14 char *c = (char*)b; // no-warning
15 char *d = b+1; // expected-warning {{never read}}
16 printf("%s", c); // expected-warning{{implicitly declaring C library function 'printf' with type 'int (char const *, ...)'}} \
17 // expected-note{{please include the header <stdio.h> or explicitly provide a declaration for 'printf'}}
18}
19
20void f3() {
21  int r;
22  if ((r = f()) != 0) { // no-warning
23    int y = r; // no-warning
24    printf("the error is: %d\n", y);
25  }
26}
27
28void f4(int k) {
29
30  k = 1;
31
32  if (k)
33    f1();
34
35  k = 2;  // expected-warning {{never read}}
36}
37
38void f5() {
39
40  int x = 4; // no-warning
41  int *p = &x; // expected-warning{{never read}}
42
43}
44
45int f6() {
46
47  int x = 4;
48  ++x; // expected-warning{{never read}}
49  return 1;
50}
51
52int f7(int *p) {
53  // This is allowed for defensive programming.
54  p = 0; // no-warning
55  return 1;
56}
57
58int f8(int *p) {
59  extern int *baz();
60  if (p = baz()) // expected-warning{{Although the value}}
61    return 1;
62  return 0;
63}
64
65int f9() {
66  int x = 4;
67  x = x + 10; // expected-warning{{never read}}
68  return 1;
69}
70
71int f10() {
72  int x = 4;
73  x = 10 + x; // expected-warning{{never read}}
74  return 1;
75}
76
77int f11() {
78  int x = 4;
79  return x++; // expected-warning{{never read}}
80}
81
82int f11b() {
83  int x = 4;
84  return ((((++x)))); // no-warning
85}
86
87int f12a(int y) {
88  int x = y;  // expected-warning{{never read}}
89  return 1;
90}
91int f12b(int y) {
92  int x __attribute__((unused)) = y;  // no-warning
93  return 1;
94}
95
96// Filed with PR 2630.  This code should produce no warnings.
97int f13(void)
98{
99  int a = 1;
100  int b, c = b = a + a;
101
102  if (b > 0)
103    return (0);
104
105  return (a + b + c);
106}
107
108// Filed with PR 2763.
109int f14(int count) {
110  int index, nextLineIndex;
111  for (index = 0; index < count; index = nextLineIndex+1) {
112    nextLineIndex = index+1;  // no-warning
113    continue;
114  }
115  return index;
116}
117
118// Test case for <rdar://problem/6248086>
119void f15(unsigned x, unsigned y) {
120  int count = x * y;   // no-warning
121  int z[count];
122}
123
124int f16(int x) {
125  x = x * 2;
126  x = sizeof(int [x = (x || x + 1) * 2]) // expected-warning{{Although the value stored to 'x' is used}}
127      ? 5 : 8;
128  return x;
129}
130
131// Self-assignments should not be flagged as dead stores.
132int f17() {
133  int x = 1;
134  x = x; // no-warning
135}
136
137// <rdar://problem/6506065>
138// The values of dead stores are only "consumed" in an enclosing expression
139// what that value is actually used.  In other words, don't say "Although the value stored to 'x' is used...".
140int f18() {
141   int x = 0; // no-warning
142   if (1)
143      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
144   while (1)
145      x = 10;  // expected-warning{{Value stored to 'x' is never read}}
146   do
147      x = 10;   // expected-warning{{Value stored to 'x' is never read}}
148   while (1);
149
150   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'}}
151}
152
153// PR 3514: false positive `dead initialization` warning for init to global
154//  http://llvm.org/bugs/show_bug.cgi?id=3514
155extern const int MyConstant;
156int f19(void) {
157  int x = MyConstant;  // no-warning
158  x = 1;
159  return x;
160}
161
162int f19b(void) { // This case is the same as f19.
163  const int MyConstant = 0;
164  int x = MyConstant; // no-warning
165  x = 1;
166  return x;
167}
168
169void f20(void) {
170  int x = 1; // no-warning
171#pragma unused(x)
172}
173
174