<html>
    <head>
      <base href="http://llvm.org/bugs/" />
    </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 function template specializations referenced from default initializers are not instantiated"
   href="http://llvm.org/bugs/show_bug.cgi?id=16008">16008</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>constexpr function template specializations referenced from default initializers are not instantiated
          </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>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>C++11
          </td>
        </tr>

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

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

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Example from DR1637:

  struct A {
    template <class T> constexpr void* f(T) { return nullptr; }
    A* ap = (A*)f(A());
    template <class ...T> constexpr A() {}
  };
  A *q = A().ap;

We do not instantiate a definition of A::f<A> here. Presumably this is because
we trigger the instantiation of the definition A::f<A> while parsing the
default initializer (before we've parsed the definition of A::f), and don't
make a note that we'll need to retry instantiation later if that instantiation
fails.

Reduced example:

  template<typename T> constexpr int f(T);          
  int k = f(0);
  template<typename T> constexpr int f(T) { return 0; }</pre>
        </div>
      </p>
      <hr>
      <span>You are receiving this mail because:</span>
      
      <ul>
          <li>You are on the CC list for the bug.</li>
      </ul>
    </body>
</html>