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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 - An example code from the standard (templates and concepts) does not compile"
   href="https://bugs.llvm.org/show_bug.cgi?id=50864">50864</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>An example code from the standard (templates and concepts) does not compile
          </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++2a
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>mikhail.matrosov@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>According to [temp.constr.decl]/4 the following example should compile:

template <class T> concept C = true;
template <class T> struct A {
  template <class U> U f(U) requires C<typename T::type>;   // #1
  template <class U> U f(U) requires C<T>;                  // #2
};

template <> template <class U>
U A<int>::f(U u) requires C<int> { return u; }              // OK, specializes
#2

However, clang gives an error:

<source>:3:49: error: type 'int' cannot be used prior to '::' because it has no
members
  template <class U> U f(U) requires C<typename T::type>;   // #1
                                                ^

I believe this is the reason why clang cannot compile libstdc++ ranges:
<a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Clang can't compile libstdc++ ranges"
   href="show_bug.cgi?id=46746">https://bugs.llvm.org/show_bug.cgi?id=46746</a></pre>
        </div>
      </p>


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