warn-loop-analysis.cpp revision 82129e25c8d26d933771bc37aa0e0ed2edd131b4 
1// RUN: %clang_cc1 -fsyntax-only -Wloop-analysis -verify %s
2
3struct S {
4  bool stop() { return false; }
5  bool keep_running;
6};
7
8void by_ref(int &value) { }
9void by_value(int value) { }
10void by_pointer(int *value) {}
11
12void test1() {
13  S s;
14  for (; !s.stop();) {}
15  for (; s.keep_running;) {}
16  for (int i; i < 1; ++i) {}
17  for (int i; i < 1; ) {}  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
18  for (int i; i < 1; ) { ++i; }
19  for (int i; i < 1; ) { return; }
20  for (int i; i < 1; ) { break; }
21  for (int i; i < 1; ) { goto exit_loop; }
22exit_loop:
23  for (int i; i < 1; ) { by_ref(i); }
24  for (int i; i < 1; ) { by_value(i); }  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
25  for (int i; i < 1; ) { by_pointer(&i); }
26
27  for (int i; i < 1; ++i)
28    for (int j; j < 1; ++j)
29      { }
30  for (int i; i < 1; ++i)
31    for (int j; j < 1; ++i)  // expected-warning {{variable 'j' used in loop condition not modified in loop body}}
32      { }
33  for (int i; i < 1; ++i)
34    for (int j; i < 1; ++j)  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
35      { }
36
37  for (int *i, *j; i < j; ++i) {}
38  for (int *i, *j; i < j;) {}  // expected-warning {{variables 'i' and 'j' used in loop condition not modified in loop body}}
39
40  // Dereferencing pointers is ignored for now.
41  for (int *i; *i; ) {}
42}
43
44void test2() {
45  int i, j, k;
46  int *ptr;
47
48  // Testing CastExpr
49  for (; i; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
50  for (; i; ) { i = 5; }
51
52  // Testing BinaryOperator
53  for (; i < j; ) {} // expected-warning {{variables 'i' and 'j' used in loop condition not modified in loop body}}
54  for (; i < j; ) { i = 5; }
55  for (; i < j; ) { j = 5; }
56
57  // Testing IntegerLiteral
58  for (; i < 5; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
59  for (; i < 5; ) { i = 5; }
60
61  // Testing FloatingLiteral
62  for (; i < 5.0; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
63  for (; i < 5.0; ) { i = 5; }
64
65  // Testing CharacterLiteral
66  for (; i == 'a'; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
67  for (; i == 'a'; ) { i = 5; }
68
69  // Testing CXXBoolLiteralExpr
70  for (; i == true; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
71  for (; i == true; ) { i = 5; }
72
73  // Testing GNUNullExpr
74  for (; ptr == __null; ) {} // expected-warning {{variable 'ptr' used in loop condition not modified in loop body}}
75  for (; ptr == __null; ) { ptr = &i; }
76
77  // Testing UnaryOperator
78  for (; -i > 5; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
79  for (; -i > 5; ) { ++i; }
80
81  // Testing ImaginaryLiteral
82  for (; i != 3i; ) {} // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
83  for (; i != 3i; ) { ++i; }
84
85  // Testing ConditionalOperator
86  for (; i ? j : k; ) {} // expected-warning {{variables 'i', 'j', and 'k' used in loop condition not modified in loop body}}
87  for (; i ? j : k; ) { ++i; }
88  for (; i ? j : k; ) { ++j; }
89  for (; i ? j : k; ) { ++k; }
90  for (; i; ) { j = i ? i : i; }  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
91  for (; i; ) { j = (i = 1) ? i : i; }
92  for (; i; ) { j = i ? i : ++i; }
93
94  // Testing BinaryConditionalOperator
95  for (; i ?: j; ) {} // expected-warning {{variables 'i' and 'j' used in loop condition not modified in loop body}}
96  for (; i ?: j; ) { ++i; }
97  for (; i ?: j; ) { ++j; }
98  for (; i; ) { j = i ?: i; }  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
99
100  // Testing ParenExpr
101  for (; (i); ) { }  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
102  for (; (i); ) { ++i; }
103
104  // Testing non-evaluated variables
105  for (; i < sizeof(j); ) { }  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
106  for (; i < sizeof(j); ) { ++j; }  // expected-warning {{variable 'i' used in loop condition not modified in loop body}}
107  for (; i < sizeof(j); ) { ++i; }
108}
109
110// False positive and how to silence.
111void test3() {
112  int x;
113  int *ptr = &x;
114  for (;x<5;) { *ptr = 6; }  // expected-warning {{variable 'x' used in loop condition not modified in loop body}}
115
116  for (;x<5;) {
117    *ptr = 6;
118    (void)x;
119  }
120}
121
122// Check ordering and printing of variables.  Max variables is currently 4.
123void test4() {
124  int a, b, c, d, e, f;
125  for (; a;);  // expected-warning {{variable 'a' used in loop condition not modified in loop body}}
126  for (; a + b;);  // expected-warning {{variables 'a' and 'b' used in loop condition not modified in loop body}}
127  for (; a + b + c;);  // expected-warning {{variables 'a', 'b', and 'c' used in loop condition not modified in loop body}}
128  for (; a + b + c + d;);  // expected-warning {{variables 'a', 'b', 'c', and 'd' used in loop condition not modified in loop body}}
129  for (; a + b + c + d + e;);  // expected-warning {{variables used in loop condition not modified in loop body}}
130  for (; a + b + c + d + e + f;);  // expected-warning {{variables used in loop condition not modified in loop body}}
131  for (; a + c + d + b;);  // expected-warning {{variables 'a', 'c', 'd', and 'b' used in loop condition not modified in loop body}}
132  for (; d + c + b + a;);  // expected-warning {{variables 'd', 'c', 'b', and 'a' used in loop condition not modified in loop body}}
133}
134
135// Ensure that the warning doesn't fail when lots of variables are used
136// in the conditional.
137void test5() {
138  for (int a; a+a+a+a+a+a+a+a+a+a;); // \
139   // expected-warning {{variable 'a' used in loop condition not modified in loop body}}
140  for (int a; a+a+a+a+a+a+a+a+a+a+a;); // \
141   // expected-warning {{variable 'a' used in loop condition not modified in loop body}}
142  for (int a; a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a;);  // \
143   // expected-warning {{variable 'a' used in loop condition not modified in loop body}}
144  for (int a; a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a+a;);//\
145   // expected-warning {{variable 'a' used in loop condition not modified in loop body}}
146}
147