<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/79783>79783</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc++][test] `array/size_and_alignment.compile.pass.cpp` includes non-Standard `<__type_traits/datasizeof.h>`
        </td>
    </tr>

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

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

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

<pre>
    Found while using MSVC's STL with libc++'s test suite.

This `libcxx/test/std/` test should be portable, but it's including a non-Standard header:

https://github.com/llvm/llvm-project/blob/86b3f8518f21532297e0aad0c6aea95c66389fc9/libcxx/test/std/containers/sequences/array/size_and_alignment.compile.pass.cpp#L25

I'm not sure if this test should be changed to be portable, or moved to the implementation-specific `libcxx/test/libcxx/` given this comment:

https://github.com/llvm/llvm-project/blob/86b3f8518f21532297e0aad0c6aea95c66389fc9/libcxx/test/std/containers/sequences/array/size_and_alignment.compile.pass.cpp#L14-L15
</pre>
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