gcc/testsuite/c-c++-common/Wtautological-compare-1.c

   1 /* PR c++/66555 */
   2 /* { dg-do compile } */
   3 /* { dg-options "-Wtautological-compare" } */
   4
   5 #define X 5
   6 #define Y 5
   7 #define A a
   8 enum { U };
   9
  10 void
  11 fn1 (int a, int *p)
  12 {
  13   if (a > a); /* { dg-warning "self-comparison always evaluates to false" } */
  14   if (a < a); /* { dg-warning "self-comparison always evaluates to false" } */
  15   if (a >= a); /* { dg-warning "self-comparison always evaluates to true" } */
  16   if (a <= a); /* { dg-warning "self-comparison always evaluates to true" } */
  17   if (a == a); /* { dg-warning "self-comparison always evaluates to true" } */
  18   if (a != a); /* { dg-warning "self-comparison always evaluates to false" } */
  19   if (A == A); /* { dg-warning "self-comparison always evaluates to true" } */
  20   if ((unsigned) a != (unsigned) a);
  21   if ((a + 1) <= (a + 1)); /* { dg-warning "self-comparison always evaluates to true" } */
  22   if (1 ? a == a : 0); /* { dg-warning "self-comparison always evaluates to true" } */
  23   if (fn1 == fn1); /* { dg-warning "self-comparison always evaluates to true" } */
  24   if (*p == *p); /* { dg-warning "self-comparison always evaluates to true" } */
  25
  26   volatile int v = 5;
  27   if (v == v);
  28   if (v != v);
  29 }
  30
  31 void
  32 fn2 (int a)
  33 {
  34   if (sizeof (int) >= 4);
  35   if (sizeof (char) != 1);
  36   if (sizeof (long) != sizeof (long long));
  37   if (0 < sizeof (short));
  38   if (5 != 5);
  39   if (X > 5);
  40   if (X == X);
  41   if (3 + 4 == 6 + 1);
  42   if ((unsigned) a != (unsigned long) a);
  43   if (U == U);
  44   if (U > 0);
  45 }
  46
  47 void
  48 fn3 (int i, int j)
  49 {
  50   static int a[16];
  51   static int b[8][8];
  52
  53   if (a[5] == a[5]);
  54   if (a[X] != a[Y]);
  55   if (a[X] != a[X]);
  56   if (a[i] == a[i]); /* { dg-warning "self-comparison always evaluates to true" } */
  57   if (b[5][5] == b[5][5]);
  58   if (b[X][Y] >= b[Y][X]);
  59   if (b[X][X] == b[Y][Y]);
  60   if (b[i][j] != b[i][j]); /* { dg-warning "self-comparison always evaluates to false" } */
  61   if (b[i][Y] < b[i][X]);
  62   if (b[X][j] < b[X][j]);
  63   if ((a[i] + 4) == (4 + a[i])); /* { dg-warning "self-comparison always evaluates to true" } */
  64 }
  65
  66 int
  67 fn4 (int x, int y)
  68 {
  69   return x > x ? 1 : 0; /* { dg-warning "self-comparison always evaluates to false" } */
  70 }