<html>
    <head>
      <base href="https://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 --- - Warn when a template class declares a dependent friend function [-Wnon-template-friend]"
   href="https://llvm.org/bugs/show_bug.cgi?id=23342">23342</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Warn when a template class declares a dependent friend function [-Wnon-template-friend]
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>All
          </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>Frontend
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>rnk@google.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The out-of-line friend declaration is very likely broken because the
declaration is not part of the template. GCC has a -Wnon-template-friend
warning that finds this.

template <typename T>
struct Arg {
  friend bool operator==(const Arg& lhs, T rhs) {
    return false;
  }

  friend bool operator!=(const Arg& lhs, T rhs);
};
template <typename T>
bool operator!=(const Arg<T>& lhs, T rhs) {
  return true;
}
bool foo() {
  Arg<int> arg;
  return (arg == 42) || (arg != 42);
}</pre>
        </div>
      </p>
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