title: Custom platforms for Visual Studio makefile project
body: <p>I have a makefile-based project and I wrote a utility to generate VS 2015 project files and hook them up to makefile commands so that I can have the best of both worlds.</p>
  
  <p>Unfortunately I've run into an issue where Visual Studio doesn't seem to allow for custom Platform names. For example, if my makefiles define two platforms, "Win32" and "Win64", upon trying to build the project in VS (which is simply making command-line calls) I get the following error:</p>
  
  <blockquote>
    <p>Error MSB8006 The Platform for project 'codegen.vcxproj' is invalid.  Platform='win64'. This error may also appear if some other project is trying to follow a project-to-project reference to this project, this project has been unloaded or is not included in the solution, and the referencing project does not build using the same or an equivalent Platform.</p>
  </blockquote>
  
  <p>If I rename win64 to x64 then it works fine, because that's a platform Visual Studio recognizes, but that doesn't solve the underlying problem which is that I don't want to be restricted to just the platforms Visual Studio is aware of. I don't understand why this would even be an issue for makefile projects since I'm not calling the compiler within Visual Studio. Does anyone know of a way to trick Visual Studio into accepting unrecognized platforms for makefile projects?</p>
  
  <p>EDIT: I can work around it by making all my configurations take the form _ and just using a placeholder like x64 for the actual platform field, but I'd still be interested in hearing if there is a real solution.</p>