gcc/testsuite/c-c++-common/Waddress-4.c

   1 /* PR c/102103 - missing warning comparing array address to null
   2    { dg-do compile }
   3    { dg-options "-Wall" } */
   4
   5 typedef __INTPTR_TYPE__ intptr_t;
   6 typedef __INTPTR_TYPE__ uintptr_t;
   7
   8 extern char *ax[], *a2[][2];
   9
  10 void T (int);
  11
  12 void test_ax_plus_eq_0 (int i)
  13 {
  14   // Verify that casts to intptr_t suppress the warning.
  15   T ((intptr_t)(ax + 0) == 0);
  16   T ((uintptr_t)(ax + 1) == 0);
  17
  18   T (ax + 0 == 0);      // { dg-warning "-Waddress" }
  19   T (&ax[0] == 0);      // { dg-warning "-Waddress" }
  20   T (ax - 1 == 0);      // { dg-warning "-Waddress" }
  21   T (0 == &ax[-1]);     // { dg-warning "-Waddress" }
  22   T ((void *)(&ax[0] + 2) == 0);  // { dg-warning "-Waddress" }
  23   T (&ax[0] + 2 == 0);  // { dg-warning "-Waddress" }
  24   T (ax + 3 == 0);      // { dg-warning "-Waddress" }
  25   T (0 == &ax[-4]);     // { dg-warning "-Waddress" }
  26   T (ax - i == 0);      // { dg-warning "-Waddress" }
  27   T (&ax[i] == 0);      // { dg-warning "-Waddress" }
  28   T (0 == &ax[1] + i);  // { dg-warning "-Waddress" }
  29 }
  30
  31 void test_a2_plus_eq_0 (int i)
  32 {
  33   // Verify that casts to intptr_t suppress the warning.
  34   T ((intptr_t)(a2 + 0) == 0);
  35   T ((uintptr_t)(a2 + 1) == 0);
  36
  37   T (a2 + 0 == 0);      // { dg-warning "-Waddress" }
  38   // Verify that a cast to another pointer type doesn't suppress it.
  39   T ((void*)(a2 + 0) == 0);       // { dg-warning "-Waddress" }
  40   T ((char*)a2 + 1 == 0);         // { dg-warning "-Waddress" }
  41   T (&a2[0] == 0);      // { dg-warning "-Waddress" }
  42   T (a2 - 1 == 0);      // { dg-warning "-Waddress" }
  43   T (0 == &a2[-1]);     // { dg-warning "-Waddress" }
  44   T (a2 + 2 == 0);      // { dg-warning "-Waddress" }
  45   T (0 == &a2[-2]);     // { dg-warning "-Waddress" }
  46   T (a2 - i == 0);      // { dg-warning "-Waddress" }
  47   T (&a2[i] == 0);      // { dg-warning "-Waddress" }
  48 }
  49
  50 // Exercise a pointer.
  51 void test_p_plus_eq_0 (int *p, int i)
  52 {
  53   /* P + 0 and equivalently &P[0] are invalid for a null P but they're
  54      folded to p before the warning has a chance to trigger.  */
  55   T (p + 0 == 0);       // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  56   T (&p[0] == 0);       // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  57
  58   T (p - 1 == 0);       // { dg-warning "-Waddress" }
  59   T (0 == &p[-1]);      // { dg-warning "-Waddress" }
  60   T (p + 2 == 0);       // { dg-warning "-Waddress" }
  61   T (0 == &p[-2]);      // { dg-warning "-Waddress" }
  62   T (p - i == 0);       // { dg-warning "-Waddress" }
  63   T (&p[i] == 0);       // { dg-warning "-Waddress" }
  64 }
  65
  66 // Exercise pointer to array.
  67 void test_pa_plus_eq_0 (int (*p)[], int (*p2)[][2], int i)
  68 {
  69   // The array pointer may be null.
  70   T (*p == 0);
  71   /* &**P is equivalent to *P and might be the result od macro expansion.
  72      Verify it doesn't cause a warning.  */
  73   T (&**p == 0);
  74
  75   /* *P + 0 is invalid but folded to *P before the warning has a chance
  76      to trigger.  */
  77   T (*p + 0 == 0);      // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  78
  79   T (&(*p)[0] == 0);    // { dg-warning "-Waddress" }
  80   T (*p - 1 == 0);      // { dg-warning "-Waddress" }
  81   T (0 == &(*p)[-1]);   // { dg-warning "-Waddress" }
  82   T (*p + 2 == 0);      // { dg-warning "-Waddress" }
  83   T (0 == &(*p)[-2]);   // { dg-warning "-Waddress" }
  84   T (*p - i == 0);      // { dg-warning "-Waddress" }
  85   T (&(*p)[i] == 0);    // { dg-warning "-Waddress" }
  86
  87
  88   /* Similar to the above but for a pointer to a two-dimensional array,
  89      referring to the higher-level element (i.e., an array itself).  */
  90   T (*p2 == 0);
  91   T (**p2 == 0);         // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  92   T (&**p2 == 0);        // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  93   T (&***p2 == 0);       // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  94   T (&**p2 == 0);
  95
  96   T (*p2 + 0 == 0);      // { dg-warning "-Waddress" "pr102555" { xfail *-*-* } }
  97   T (&(*p2)[0] == 0);    // { dg-warning "-Waddress" }
  98   T (&(*p2)[0][1] == 0); // { dg-warning "-Waddress" }
  99   T (*p2 - 1 == 0);      // { dg-warning "-Waddress" }
 100   T (0 == &(*p2)[-1]);   // { dg-warning "-Waddress" }
 101   T (0 == &(*p2)[1][2]); // { dg-warning "-Waddress" }
 102   T (*p2 + 2 == 0);      // { dg-warning "-Waddress" }
 103   T (0 == &(*p2)[-2]);   // { dg-warning "-Waddress" }
 104   T (*p2 - i == 0);      // { dg-warning "-Waddress" }
 105   T (&(*p2)[i] == 0);    // { dg-warning "-Waddress" }
 106 }