gcc/testsuite/gcc.dg/Warray-bounds-80.c

   1 /* PR tree-optimization/101397 - spurious warning writing to the result
   2    of stpcpy minus 1
   3    { dg-do compile }
   4    { dg-options "-O2 -Wall" } */
   5
   6 char* stpcpy (char*, const char*);
   7
   8 void sink (int, ...);
   9
  10 extern char ax[], a3[3], a5[5], *s;
  11
  12 volatile int x;
  13
  14 void test_stpcpy (int i)
  15 {
  16   {
  17     char *p = stpcpy (ax, s);
  18     x = p[-9];                          // { dg-bogus "\\\[-Warray-bounds" }
  19     x = p[-1];                          // { dg-bogus "\\\[-Warray-bounds" }
  20     x = p[ 0];
  21     x = p[+9];
  22   }
  23
  24   {
  25     char *p = stpcpy (a3, s);
  26     x = p[-2];                          // { dg-bogus "\\\[-Warray-bounds" }
  27     x = p[-1];                          // { dg-bogus "\\\[-Warray-bounds" }
  28   }
  29
  30   {
  31     char *p = stpcpy (a3, s);
  32     x = p[-3];                          // { dg-warning "\\\[-Warray-bounds" }
  33     sink (p[-2], p[-1], p[0], p[1], p[2]);
  34     x = p[ 3];                          // { dg-warning "\\\[-Warray-bounds" }
  35   }
  36
  37   {
  38     /* Stpcpy always returns a pointer to the copied nul (which must
  39        exist) and never a past-the-end pointer.  As a result, P below
  40        is in [a5, a5 + 4].  */
  41     char *p = stpcpy (a5, s);
  42     x = p[-5];                          // { dg-warning "\\\[-Warray-bounds" }
  43     sink (p[-4], p[-3], p[-2], p[-1], p[0]);
  44     sink (p[1], p[2], p[3], p[4]);
  45     x = p[ 5];                          // { dg-warning "\\\[-Warray-bounds" }
  46   }
  47
  48   {
  49     char *p = stpcpy (a5 + 1, s);
  50     x = p[-5];                          // { dg-warning "\\\[-Warray-bounds" }
  51     sink (p[-4], p[-3], p[-2], p[-1], p[0]);
  52     sink (p[1], p[2], p[3]);
  53     x = p[ 4];                          // { dg-warning "\\\[-Warray-bounds" }
  54   }
  55
  56   {
  57     char *p = stpcpy (a5 + 2, s);
  58     x = p[-5];                          // { dg-warning "\\\[-Warray-bounds" }
  59     sink (p[-4], p[-3], p[-2], p[-1], p[0]);
  60     sink (p[1], p[2]);
  61     x = p[ 3];                          // { dg-warning "\\\[-Warray-bounds" }
  62   }
  63
  64   {
  65     char *p = stpcpy (a5 + 3, s);
  66     x = p[-5];                          // { dg-warning "\\\[-Warray-bounds" }
  67     sink (p[-4], p[-3], p[-2], p[-1], p[0]);
  68     sink (p[1]);
  69     x = p[ 2];                          // { dg-warning "\\\[-Warray-bounds" }
  70   }
  71
  72   {
  73     /* Because strlen (a3) is at most 2, the stpcpy call must return
  74        a pointer in the range [ax, ax + 2], and so -3 is necessarily
  75        out of bounds.  */
  76     char *p = stpcpy (ax, a3);
  77     p[-3] = 1;                          // { dg-warning "\\\[-Warray-bounds" }
  78   }
  79
  80   {
  81     if (i >= 0)
  82       i = -1;
  83
  84     char *p = stpcpy (a3, s);
  85     x = p[i];                           // { dg-bogus "\\\[-Warray-bounds" }
  86   }
  87
  88   {
  89     if (i >= -3)
  90       i = -3;
  91
  92     char *p = stpcpy (a3, s);
  93     p[i] = 1;                           // { dg-warning "\\\[-Warray-bounds" }
  94   }
  95
  96 }