<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/128627>128627</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            libc++ hardening mode doesn't detect
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          thesamesam
      </td>
    </tr>
</table>

<pre>
    Noticed when reading https://jacko.io/smart_pointers.html.

libc++'s hardening mode doesn't detect the following, even with `-D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_DEBUG`, while `-D_GLIBCXX_DEBUG` (though not `-D_GLIBCXX_ASSERTIONS` does):

```c++
#include <vector>

int main() {
    std::vector<int> my_vector = {1, 2, 3};
    for (auto element : my_vector) {
        if (element == 2) {
            my_vector.push_back(4);
            /* The next loop iteration reads a dangling pointer. */
        }
 }
}
```

godbolt: https://godbolt.org/z/jKaYPY3vb
</pre>
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