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    <head>
      <base href="http://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 - constexpr variable template requires default initialization even though it's not instantiated"
   href="http://bugs.llvm.org/show_bug.cgi?id=32115">32115</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>constexpr variable template requires default initialization even though it's not instantiated
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>3.9
          </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>C++14
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>arnetheduck@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>clang rejects the following snippet:

template <typename T>
constexpr int kTag;

with the error:

default initialization of an object of const type 'const int'

even thought it's never instantiated - gcc (6.2) accepts the same code.

I'm not sure if gcc or clang is at fault, per the standard, but seems
reasonable that the error should be delayed until instantiation - that would be
consistent with a constexpr function for example that can remain undefined
unless it's actually used.

Eventually, I'm looking to specialize the tag for different type and letting
the compile catch any untagged types.</pre>
        </div>
      </p>


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