test/Sema/warn-overlap.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160

// RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-overlap-compare %s

#define mydefine 2

enum Choices {
  CHOICE_0 = 0,
  CHOICE_1 = 1
};

enum Unchoices {
  UNCHOICE_0 = 0,
  UNCHOICE_1 = 1
};

void f(int x) {
  int y = 0;

  // > || <
  if (x > 2 || x < 1) { }
  if (x > 2 || x < 2) { }
  if (x != 2 || x != 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x > 2 || x < 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x > 0 || x < 0) { }

  if (x > 2 || x <= 1) { }
  if (x > 2 || x <= 2) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x > 2 || x <= 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}

  if (x >= 2 || x < 1) { }
  if (x >= 2 || x < 2) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x >= 2 || x < 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}

  if (x >= 2 || x <= 1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x >= 2 || x <= 2) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x >= 2 || x <= 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x >= 0 || x <= 0) { } // expected-warning {{overlapping comparisons always evaluate to true}}

  // > && <
  if (x > 2 && x < 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x > 2 && x < 2) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x > 2 && x < 3) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x > 0 && x < 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}

  if (x > 2 && x <= 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x > 2 && x <= 2) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x > 2 && x <= 3) { }

  if (x >= 2 && x < 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x >= 2 && x < 2) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x >= 2 && x < 3) { }
  if (x >= 0 && x < 0) { }  // expected-warning {{overlapping comparisons always evaluate to false}}

  if (x >= 2 && x <= 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x >= 2 && x <= 2) { }
  if (x >= 2 && x <= 3) { }

  // !=, ==, ..
  if (x != 2 || x != 3) { }  // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x != 2 || x < 3) { }   // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x == 2 && x == 3) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x == 2 && x > 3) { }   // expected-warning {{overlapping comparisons always evaluate to false}}
  if (x == 3 && x < 0) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  if (3 == x && x < 0) { }  // expected-warning {{overlapping comparisons always evaluate to false}}

  if (x == mydefine && x > 3) { }
  if (x == (mydefine + 1) && x > 3) { }

  if (x != CHOICE_0 || x != CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (x == CHOICE_0 && x == CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to false}}

  // Don't warn if comparing x to different types
  if (x == CHOICE_0 && x == 1) { }
  if (x != CHOICE_0 || x != 1) { }

  // "Different types" includes different enums
  if (x == CHOICE_0 && x == UNCHOICE_1) { }
  if (x != CHOICE_0 || x != UNCHOICE_1) { }
}

void enums(enum Choices c) {
  if (c != CHOICE_0 || c != CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  if (c == CHOICE_0 && c == CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to false}}

  // Don't warn if comparing x to different types
  if (c == CHOICE_0 && c == 1) { }
  if (c != CHOICE_0 || c != 1) { }

  // "Different types" includes different enums
  if (c == CHOICE_0 && c == UNCHOICE_1) { }
  if (c != CHOICE_0 || c != UNCHOICE_1) { }
}

// Don't generate a warning here.
void array_out_of_bounds() {
  int x;
  int buffer[4];
  x = (-7 > 0) ? (buffer[-7]) : 0;
}

void bool_contexts(int x) {
  if (x > 4 || x < 10) {}
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  for (;x > 4 || x < 10;) {}
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  while (x > 4 || x < 10) {}
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  do {} while (x > 4 || x < 10);
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  x = (x > 4 || x < 10) ? 1 : 2;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  if ((void)5, x > 4 || x < 10) {}
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
}

void assignment(int x) {
  int a = x > 4 || x < 10;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  int b = x < 2 && x > 5;
  // expected-warning@-1{{overlapping comparisons always evaluate to false}}

  int c = x != 1 || x != 3;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  int d = x == 1 && x == 2;
  // expected-warning@-1{{overlapping comparisons always evaluate to false}}

  int e = x < 1 || x != 0;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
}

int returns(int x) {
  return x > 4 || x < 10;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  return x < 2 && x > 5;
  // expected-warning@-1{{overlapping comparisons always evaluate to false}}

  return x != 1 || x != 3;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  return x == 1 && x == 2;
  // expected-warning@-1{{overlapping comparisons always evaluate to false}}

  return x < 1 || x != 0;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
}

int integer_conversion(unsigned x, int y) {
  return x > 4 || x < 10;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
  return y > 4u || y < 10u;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
}

int negative_compare(int x) {
  return x > -1 || x < 1;
  // expected-warning@-1{{overlapping comparisons always evaluate to true}}
}

int no_warning(unsigned x) {
  return x >= 0 || x == 1;
  // no warning since "x >= 0" is caught by a different tautological warning.
}