gcc/testsuite/gcc.dg/pr80776-1.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -Wformat-overflow" } */
   3
   4 extern __inline __attribute__ ((__always_inline__)) __attribute__ ((__gnu_inline__)) __attribute__ ((__artificial__)) int
   5 __attribute__ ((__nothrow__ , __leaf__)) sprintf (char *__restrict __s, const char *__restrict __fmt, ...)
   6 {
   7   return __builtin___sprintf_chk (__s, 2 - 1,
   8                                   __builtin_object_size (__s, 2 > 1), __fmt, __builtin_va_arg_pack ());
   9 }
  10 char number[sizeof "999999"];
  11 int somerandom (void);
  12 void
  13 Foo (void)
  14 {
  15   int i = somerandom ();
  16   if (! (0 <= i))
  17     __builtin_unreachable ();
  18   if (! (0 <= i && i <= 999999))
  19     __builtin_unreachable ();
  20
  21   /* Legacy evrp sets the range of i to [0, MAX] *before* the first conditional,
  22      and to [0,999999] *before* the second conditional.  This is because both
  23      evrp and VRP use trickery to set global ranges when this particular use of
  24      a __builtin_unreachable is in play (see uses of
  25      assert_unreachable_fallthru_edge_p).
  26
  27      Setting these ranges at the definition site, causes VRP to remove the
  28      unreachable code altogether, leaving the following sprintf unguarded.  This
  29      causes the bogus warning below.  */
  30   sprintf (number, "%d", i); /* { dg-bogus "writing" "" } */
  31 }