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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Crash on compiling invalid requires expression"
   href="https://bugs.llvm.org/show_bug.cgi?id=47582">47582</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Crash on compiling invalid requires expression
          </td>
        </tr>

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

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

        <tr>
          <th>Hardware</th>
          <td>Macintosh
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>MacOS X
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>C++2a
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>marian.darius98@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=23984" name="attach_23984" title="Files requested by the compiler in the crash message.">attachment 23984</a> <a href="attachment.cgi?id=23984&action=edit" title="Files requested by the compiler in the crash message.">[details]</a></span>
Files requested by the compiler in the crash message.

While writing an experimental implementation of std::is_polymorphic using a
requires expression, I made a small mistake in the program. I was expecting a
compile error, but Clang crashed instead (with an assertion failure):

template<class T>
inline constexpr bool is_polymorphic = requires {
  typename dynamic_cast<const volatile void*>(declval<T*>());
};

The expected output is a compile error (I strongly believe), the code is an
invalid usage of the requires { typename ... } clause.

I attached a bundle with all the files required by the crash. Since it was
fully reproducible, I minimized the example as much as I could.
"clang-crash.cpp" is the original source code, "cli-output.txt" is the console
output for running the command, and the other attachments are files requested
in the output of the compiler.</pre>
        </div>
      </p>


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