<html>
    <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 - invalid application of 'sizeof' to an incomplete type 'B<typename std::decay<int>::type>' (aka 'B<int>')"
   href="https://bugs.llvm.org/show_bug.cgi?id=31976">31976</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>invalid application of 'sizeof' to an incomplete type 'B<typename std::decay<int>::type>' (aka 'B<int>')
          </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>normal
          </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>ajneu1@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The following code, when compiled with
clang++-3.9 -std=c++14 -o go main.cpp

gives this error:
error: invalid application of 'sizeof' to an incomplete type 'B<typename
std::decay<int>::type>' (aka 'B<int>')

See <a href="http://melpon.org/wandbox/permlink/vMiEuyYyKk9Ya4aX">http://melpon.org/wandbox/permlink/vMiEuyYyKk9Ya4aX</a>

But it works find with gcc: <a href="http://melpon.org/wandbox/permlink/xmSu58FRGFTm84RW">http://melpon.org/wandbox/permlink/xmSu58FRGFTm84RW</a>

///////////////////////////////////////////////
#include <iostream>

template <typename T1>
struct A {


  template <typename T2>
  struct B {
  public:
    static const std::size_t Size = (sizeof(B<typename std::decay<T2>::type>));

    /*
      // workaround
    static constexpr std::size_t Size() {
      return (sizeof(B<typename std::decay<T2>::type>));
    }
    */

  private:
    T2 t_;
  };


};



int main()
{
  std::cout << A<int>::B<int>::Size << std::endl;

  return 0;
}

///////////////////////////////////////////////</pre>
        </div>
      </p>


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