title: Who copies app.config to app.exe.config?
body: <p>I'm writing a game development IDE that creates and compiles .NET projects (which I've been working on for the past few years) and am in the process of updating it to generate output not only for Windows/Visual Studio, but also for Linux/MonoDevelop (a thrillingly simple process for .NET, but still requiring some tweaks). </p>
  
  <p>As part of this, I have found it necessary to start generating an app.config file as part of this to map dependent DLL names to Linux dependency names with &lt;dllmap&gt; elements.  I'm confused about who's responsible for copying the app.config file to the output name app.exe.config. In a Visual Studio project, the Build Action for app.config seems to normally be set to "None" and its settings indicate that it won't be copied anywhere, yet when Visual Studio compiles the project it generates app.exe.config (though I've sometimes found this to be unreliable).  When I use MSBuild to build a solution file generated by the IDE (for debugging purposes), MSBuild copies app.config to app.exe.config.  But when I compile the project with CSharpCodeProvider.CompileAssemblyFromFile it (naturally) doesn't like the config file being included as source code ("app.config(1,1) : error CS0116: A namespace does not directly contain members such as fields or methods"), and of course it doesn't copy it to the output when I don't include it as an input.  Is it my responsibility to simply copy app.config to app.exe.config independently, or is there a more standard way of doing this?</p>
  
  <p>Is it hardwired to take the first *.config file?  In my IDE it's conceivable that the app.config file would be renamed or another one added (just as in Visual Studio).  It seems odd to me that the IDE has this secret action for config files (I think MonoDevelop behaves similarly in this regard because I couldn't find a special action for config files there either). I don't know how it even picks to what files this secret action applies.</p>