<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/68489>68489</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            `enum-constexpr-conversion` inconsistently raised in variadic/non-variadic NTTP contexts
        </td>
    </tr>

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

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

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

<pre>
    Hey,

Clang 16 introduced a potentially breaking change affecting enums with no underlying type explicitly specified ([Discourse](https://discourse.llvm.org/t/clang-16-notice-of-potentially-breaking-changes/65562)). Unfortunately this is not SFINAE friendly yet (https://github.com/llvm/llvm-project/issues/57176). 

During reserach I've seen various enum "reflection" libraries sidestep this new diagnostic by converting from floats (https://github.com/llvm/llvm-project/issues/58127#issuecomment-1673662280) or by using `__builtin_bit_cast` or, well `std::bit_cast` (for example see [magic_enum](https://github.com/Neargye/magic_enum/blob/master/include/magic_enum.hpp#L623-L628)).


I noticed clang behaves inconsistently depending on whether a result of a conversion like that is used in a pack or not. https://godbolt.org/z/T6T8ohqvv here's a code example.
</pre>
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