<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/150340>150340</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang incorrectly allows converting function pointers to and from void* in constant expressions
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:frontend,
            constexpr
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          efriedma-quic
      </td>
    </tr>
</table>

<pre>
    Consider:

```
void f();
constexpr auto p1 = (void*)f;
constexpr auto p2 = (void(*)())p1;
```

clang currently accepts, but these should be rejected. [expr.const] says an expression is not a constant expression if it contains a reinterpret_cast ... and converting a function pointer to an object pointer requires a reinterpret_cast.

gcc rejects, MSVC accepts p1.
</pre>
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