<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/107789>107789</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            span does not check or null on construction in hardening modes
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    The following code in hardening does not check that the range is valid when it can.  null, 0 is valid but null, N > 0 is UB

```cpp
int main( ) {
    constexpr int * p = nullptr;
 return foo( std::span<int>(p, 5) );
}
``` 

should error with a check that if It is null, size == 0 
</pre>
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