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      <base href="https://bugs.llvm.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - clang ODR checker errors on (real) ODR violation in libstdc++ headers"
   href="https://bugs.llvm.org/show_bug.cgi?id=38920">38920</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>clang ODR checker errors on (real) ODR violation in libstdc++ headers
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Modules
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>rtrieu@google.com
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>richard-llvm@metafoo.co.uk
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Our libstdc++ / modules buildbot is currently failing due to the modules ODR
checker finding a ODR violation in a libstdc++ header:

<a href="http://lab.llvm.org:8011/builders/clang-x86_64-linux-selfhost-modules-2/builds/26164/steps/compile.llvm.stage2/logs/stdio">http://lab.llvm.org:8011/builders/clang-x86_64-linux-selfhost-modules-2/builds/26164/steps/compile.llvm.stage2/logs/stdio</a>

There is a real ODR violation in this code. std::_Sp_counted_base::_M_release
calls __gnu_cxx::__exchange_and_add_dispatch, which is declared static.

While this is a bug in libstdc++, we do aim to support libstdc++ regardless of
its bugs, and so we should work around this. Assuming the above ODR violation
is indeed the reason that the check is failing, we could special-case this
particular function name when computing ODR hashes, and ensure that it always
hashes to the same value even when resolving to two different functions in
different translation units.</pre>
        </div>
      </p>


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