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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109175] error: 'void* __builtin_memset(void*,
 int, long unsigned int)' writing 4 or more bytes into a region of size 0
 overflows the destination [-Werror=stringop-overflow=]
Date: Fri, 24 Mar 2023 18:46:49 +0000
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X-Bugzilla-Component: tree-optimization
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X-Bugzilla-Keywords: diagnostic, needs-reduction
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109175

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced all the way removing all of the classes showing exactly what I thou=
ght
it was:
```
void *ao();
float *aq(long t) {
  if (t)
    return nullptr;
  return static_cast<float *>(ao());
}
float v;
void at(long t) {
  long a =3D sizeof(0), i =3D 0;
  auto b =3D aq(t);
  for (; i < a; ++i)
    b[i] =3D v;
  for (; i < t; ++i)
    b[i] =3D 0.0f;
}
```

Notice how there is no check for null on aq.=