gcc/testsuite/gcc.dg/Wstringop-overflow-21.c

/* PR middle-end/92312 - bogus -Wstringop-overflow storing into a trailing
   array backed by larger buffer
   { dg-do compile }
   { dg-options "-O2 -Wall -Wno-array-bounds" } */

struct S0 { char a, b[0]; };

void sink (void*);

void test_memset_zero_length (void)
{
  char a[3];
  struct S0 *p = (struct S0*)a;
  p->a = 0;
  __builtin_memset (p->b, 0, 2);
  sink (p);

  __builtin_memset (p->b, 0, 3);    // { dg-warning "\\\[-Wstringop-overflow" }
  sink (p);
}

void test_store_zero_length (int i)
{
  char a[3];
  struct S0 *p = (struct S0*)a;
  p->a = 0;
  p->b[0] = 0;
  p->b[1] = 1;                      // { dg-bogus "\\\[-Wstringop-overflow" }
  p->b[2] = 2;                      // { dg-warning "\\\[-Wstringop-overflow" }
  p->b[i] = 2;
  sink (p);
}


struct Sx { char a, b[]; };

void test_memset_flexarray (int i)
{
  char a[3];
  struct Sx *p = (struct Sx*)a;
  p->a = 0;
  __builtin_memset (p->b, 0, 2);
  sink (p);

  __builtin_memset (p->b, 0, 3);    // { dg-warning "\\\[-Wstringop-overflow" }
  sink (p);
}

void test_store_flexarray (int i)
{
  char a[3];
  struct Sx *p = (struct Sx*)a;
  p->a = 0;
  p->b[0] = 0;
  p->b[1] = 1;                      // { dg-bogus "\\\[-Wstringop-overflow" }
  p->b[2] = 1;                      // { dg-warning "\\\[-Wstringop-overflow" }
  p->b[i] = 2;
  sink (p);
}