<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/149041>149041</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Clang] -Winvalid-constexpr misbehaves in C++23 mode
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:frontend,
            regression,
            rejects-valid,
            constexpr
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          frederick-vs-ja
      </td>
    </tr>
</table>

<pre>
    In C++23/26 mode, Clang rejects the following function definition with `-Winvalid-constexpr` used, saying "constexpr function never produces a constant expression". [Godbolt link](https://godbolt.org/z/WaKPMjorP).
```C++
constexpr bool fun(const bool& b) { return b; }
```

This seems related to [P2280R4](https://wg21.link/p2280r4), but the incorrect diagnostic occurs only since Clang 21.
</pre>
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