title: How to use make_unique in clang 3.4?
body: <p>Using <code>Travis-CI</code> I'm trying to build a C++ project that uses <code>std::make_unique</code>. However I get a build error:</p>
  
  <pre><code>no member named 'make_unique' in namespace 'std'
              mFiles.emplace_back(std::make_unique&lt;File&gt;(*this, rec));
  </code></pre>
  
  <p>I have included <code>memory</code>, and this code compiles in VS2013 and gcc 4.8 with <code>-std=c++14</code>. If I use this flag in clang 3.4 I get an error:</p>
  
  <pre><code>error: invalid value 'c++14' in '-std=c++14'
  </code></pre>
  
  <p>According the the clang docs:</p>
  
  <p><a href="http://clang.llvm.org/cxx_status.html" rel="nofollow">http://clang.llvm.org/cxx_status.html</a></p>
  
  <p>I should be using <code>-std=c++1y</code> but this still yeilds the same <code>no member named 'make_unique' in namespace 'std'</code>. So how do I get it to work?</p>