clang/test/Sema/warn-overlap.c

   1 // RUN: %clang_cc1 -fsyntax-only -verify -Wtautological-overlap-compare %s
   2 // RUN: %clang_cc1 -fsyntax-only -verify -Wall -Wno-unused -Wno-loop-analysis %s
   3
   4 #define mydefine 2
   5
   6 enum Choices {
   7   CHOICE_0 = 0,
   8   CHOICE_1 = 1
   9 };
  10
  11 enum Unchoices {
  12   UNCHOICE_0 = 0,
  13   UNCHOICE_1 = 1
  14 };
  15
  16 void f(int x) {
  17   int y = 0;
  18
  19   // > || <
  20   if (x > 2 || x < 1) { }
  21   if (x > 2 || x < 2) { }
  22   if (x != 2 || x != 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  23   if (x > 2 || x < 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  24   if (x > 0 || x < 0) { }
  25
  26   if (x > 2 || x <= 1) { }
  27   if (x > 2 || x <= 2) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  28   if (x > 2 || x <= 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  29
  30   if (x >= 2 || x < 1) { }
  31   if (x >= 2 || x < 2) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  32   if (x >= 2 || x < 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  33
  34   if (x >= 2 || x <= 1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  35   if (x >= 2 || x <= 2) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  36   if (x >= 2 || x <= 3) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  37   if (x >= 0 || x <= 0) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  38
  39   // > && <
  40   if (x > 2 && x < 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  41   if (x > 2 && x < 2) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  42   if (x > 2 && x < 3) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  43   if (x > 0 && x < 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  44
  45   if (x > 2 && x <= 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  46   if (x > 2 && x <= 2) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  47   if (x > 2 && x <= 3) { }
  48
  49   if (x >= 2 && x < 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  50   if (x >= 2 && x < 2) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  51   if (x >= 2 && x < 3) { }
  52   if (x >= 0 && x < 0) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  53
  54   if (x >= 2 && x <= 1) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  55   if (x >= 2 && x <= 2) { }
  56   if (x >= 2 && x <= 3) { }
  57
  58   // !=, ==, ..
  59   if (x != 2 || x != 3) { }  // expected-warning {{overlapping comparisons always evaluate to true}}
  60   if (x != 2 || x < 3) { }   // expected-warning {{overlapping comparisons always evaluate to true}}
  61   if (x == 2 && x == 3) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  62   if (x == 2 && x > 3) { }   // expected-warning {{overlapping comparisons always evaluate to false}}
  63   if (x == 3 && x < 0) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  64   if (3 == x && x < 0) { }  // expected-warning {{overlapping comparisons always evaluate to false}}
  65
  66   if (x == mydefine && x > 3) { }
  67   if (x == (mydefine + 1) && x > 3) { }
  68
  69   if (x != CHOICE_0 || x != CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  70   if (x == CHOICE_0 && x == CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to false}}
  71
  72   // Don't warn if comparing x to different types
  73   if (x == CHOICE_0 && x == 1) { }
  74   if (x != CHOICE_0 || x != 1) { }
  75
  76   // "Different types" includes different enums
  77   if (x == CHOICE_0 && x == UNCHOICE_1) { }
  78   if (x != CHOICE_0 || x != UNCHOICE_1) { }
  79 }
  80
  81 void enums(enum Choices c) {
  82   if (c != CHOICE_0 || c != CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to true}}
  83   if (c == CHOICE_0 && c == CHOICE_1) { } // expected-warning {{overlapping comparisons always evaluate to false}}
  84
  85   // Don't warn if comparing x to different types
  86   if (c == CHOICE_0 && c == 1) { }
  87   if (c != CHOICE_0 || c != 1) { }
  88
  89   // "Different types" includes different enums
  90   if (c == CHOICE_0 && c == UNCHOICE_1) { }
  91   if (c != CHOICE_0 || c != UNCHOICE_1) { }
  92 }
  93
  94 // Don't generate a warning here.
  95 void array_out_of_bounds(void) {
  96   int x;
  97   int buffer[4];
  98   x = (-7 > 0) ? (buffer[-7]) : 0;
  99 }
 100
 101 void bool_contexts(int x) {
 102   if (x > 4 || x < 10) {}
 103   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 104   for (;x > 4 || x < 10;) {}
 105   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 106   while (x > 4 || x < 10) {}
 107   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 108   do {} while (x > 4 || x < 10);
 109   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 110   x = (x > 4 || x < 10) ? 1 : 2;
 111   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 112   if ((void)5, x > 4 || x < 10) {}
 113   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 114 }
 115
 116 void assignment(int x) {
 117   int a = x > 4 || x < 10;
 118   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 119   int b = x < 2 && x > 5;
 120   // expected-warning@-1{{overlapping comparisons always evaluate to false}}
 121
 122   int c = x != 1 || x != 3;
 123   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 124   int d = x == 1 && x == 2;
 125   // expected-warning@-1{{overlapping comparisons always evaluate to false}}
 126
 127   int e = x < 1 || x != 0;
 128   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 129 }
 130
 131 int returns(int x) {
 132   return x > 4 || x < 10;
 133   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 134   return x < 2 && x > 5;
 135   // expected-warning@-1{{overlapping comparisons always evaluate to false}}
 136
 137   return x != 1 || x != 3;
 138   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 139   return x == 1 && x == 2;
 140   // expected-warning@-1{{overlapping comparisons always evaluate to false}}
 141
 142   return x < 1 || x != 0;
 143   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 144 }
 145
 146 int integer_conversion(unsigned x, int y) {
 147   return x > 4 || x < 10;
 148   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 149   return y > 4u || y < 10u;
 150   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 151 }
 152
 153 int negative_compare(int x) {
 154   return x > -1 || x < 1;
 155   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 156 }
 157
 158 int no_warning(unsigned x) {
 159   return x >= 0 || x == 1;
 160   // no warning since "x >= 0" is caught by a different tautological warning.
 161 }
 162
 163 struct A {
 164   int x;
 165   int y;
 166 };
 167
 168 int struct_test(struct A a) {
 169   return a.x > 5 && a.y < 1;  // no warning, different variables
 170
 171   return a.x > 5 && a.x < 1;
 172   // expected-warning@-1{{overlapping comparisons always evaluate to false}}
 173   return a.y == 1 || a.y != 1;
 174   // expected-warning@-1{{overlapping comparisons always evaluate to true}}
 175 }