title: Clang targeting WebAssembly(--target=wasm64) on Windows could not find C++ headers
body: <p>I have clang 11.0.0 installed on Windows 7. I used clang++ to compile a simple helloworld.cpp and no problem:</p>
  <blockquote>
  <p>clang++ helloworld.cpp -c</p>
  </blockquote>
  <p>Now my goal is to target WebAssembly, so I ran:</p>
  <blockquote>
  <p>clang++ helloworld.cpp <strong>--target=wasm32</strong> -c</p>
  </blockquote>
  <p>This gave me error &quot;iostream file not found&quot;. I used verbose to see that the include path had:</p>
  <blockquote>
  <p>ignoring nonexistent directory &quot;<strong>/include/wasm64-wasi/c++/v1</strong>&quot;<br />
  ignoring nonexistent directory &quot;<strong>/include/c++/v1</strong>&quot;<br />
  ignoring nonexistent directory &quot;/include/wasm64-wasi&quot;<br />
  ignoring nonexistent directory &quot;/include&quot;<br />
  #include &quot;...&quot; search starts here:<br />
  #include &lt;...&gt; search starts here:<br />
  C:\LLVM\lib\clang\11.0.0\include<br />
  End of search list.</p>
  </blockquote>
  <p>It seems that clang is trying to look under these linux style include paths where C++ headers can be found, however I am using Windows.</p>
  <p>As mentioned, it works without targeting wasm, meaning clang knows to look under Windows style VC++ include paths. Is there a way to look under VC++ include paths with --target=wasm64 specified? BTW I do have MinGW installed and in PATH environemnt variable.</p>
  <p>Using <strong>Emscripten</strong> I was able to make it work since Emscripten had C++ headers in its own installation. However still curious if it is possible using only clang.</p>