title: clang++ -stdlib=libc++ leads to undefined reference
body: <p>Why am I getting the following linker error when using clang with libc++:</p>
  
  <pre><code>$ clang++ -stdlib=libc++  po.cxx -lpoppler
  /tmp/po-QqlXGY.o: In function `main':
  po.cxx:(.text+0x33): undefined reference to `Dict::lookup(char*, Object*, std::__1::set&lt;int, std::__1::less&lt;int&gt;, std::__1::allocator&lt;int&gt; &gt;*)'
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>Where:</p>
  
  <pre><code>$ nm -D /usr/lib/x86_64-linux-gnu/libpoppler.so | grep lookup | c++filt| grep \ Dict::lookup\(
  00000000000c1870 T Dict::lookup(char*, Object*, std::set&lt;int, std::less&lt;int&gt;, std::allocator&lt;int&gt; &gt;*)
  </code></pre>
  
  <p>Code is simply:</p>
  
  <pre><code>#include &lt;poppler/PDFDoc.h&gt;
  
  int main()
  {
    Dict *infoDict;
    Object obj;
    infoDict-&gt;lookup((char*)"key", &amp;obj);
    return 0;
  }
  </code></pre>