title: Why isn't __clang__ defined when using LLVM+Clang in Visual Studio?
body: <p>I installed LLVM for Windows, which includes Clang and a few other tools. It integrates with Visual Studio, and even lets me choose a "Platform Toolset" in the project properties. However, when I choose any of the toolsets that came with LLVM, <code>__clang__</code> isn't defined, and <code>_MSC_VER</code> is defined instead. How do I make <code>__clang__</code> defined when using LLVM and Clang in Visual Studio?</p>
  
  <p>My Visual Studio version is the 2015 Preview (however I have also tested on 2013 with no success either), and my LLVM version is based off of SVN release 225473. I've tried <code>LLVM-vs2012</code>, <code>LLVM-vs2013</code>, and <code>LLVM-vs2014</code> as the Platform Toolset without success.</p>