<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 --- - Missing diagnostic for return of std::unique_ptr<Derived> in C++11"
   href="https://llvm.org/bugs/show_bug.cgi?id=31461">31461</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Missing diagnostic for return of std::unique_ptr<Derived> in C++11
          </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>vmpstr@chromium.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Consider the following

#include <memory>

struct A {};
struct B : public A {};

std::unique_ptr<A> f() {
  auto result = std::unique_ptr<B>(new B);
  return result;
}

In C++11, the return line has to have an std::move, since the type of |result|
doesn't match the return type of the function.

However, it compiles with current clang++

Expected:
=========
$ clang++ -std=c++11 -c test.cpp
test.cpp:8:10: error: no viable conversion from 'unique_ptr<struct B,
default_delete<struct B>>' to 'unique_ptr<struct A, default_delete<struct A>>'
  return result;
         ^~~~~~
...
$ clang++ --version
clang version 3.9.0 (trunk 273760)
...


Actual:
=======
$ clang++ -std=c++11 -c test.cpp
$ clang++ --version
clang version 3.9.0 (trunk 274367)
...

Since C++14 does allow this to compile, I suspect that
<a href="http://reviews.llvm.org/D21619">http://reviews.llvm.org/D21619</a> inadvertently caused this.</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>