anchor.diff:                        yield "--define:DEBUG" 
                         //yield "--optimize-" 
                         yield "--nooptimizationdata"
  -                      if hasCoreLib then
  -                        yield "--noframework"
  +                      yield "--noframework"
  +                      if msCoreLib.IsSome then
  +                        yield sprintf "-r:%s" msCoreLib.Value
  +                      if fsCoreLib.IsSome then
  +                        yield sprintf "-r:%s" fsCoreLib.Value
                         yield "--out:" + dllName
                         yield "--doc:" + xmlName
                         yield "--warn:3" 
  
positive.code:   module internal FSharpAssemblyHelper =
        open System.IO
        let checker = FSharpChecker.Create()
            
        let getProjectReferences otherFlags libDirs dllFiles = 
            let dllFiles, hasCoreLib =
              dllFiles
              |> Seq.fold (fun (files, hasCoreLib) dllFile -> 
                 dllFile :: files, 
                 hasCoreLib || 
                 let name = (Path.GetFileName dllFile).ToLowerInvariant()
                 let iscorelib = name = "fsharp.core.dll" || name = "mscorlib.dll" 
                 printfn "%s is corlib: %b" dllFile iscorelib
                 iscorelib
              ) ([], false)
  
            let otherFlags = defaultArg otherFlags Seq.empty
            let libDirs = defaultArg libDirs Seq.empty
            let base1 = Path.GetTempFileName()
  
negative.code:           let isWindows = System.Environment.OSVersion.Platform = System.PlatformID.Win32NT
            let loc =
                if isWindows && assembly.GetName().Name = "FSharp.Core" then
                    FSharpAssemblyHelper.fsCore4300()
                    // TODO: handle more cases / versions.
                    // file references only valid on Windows 
                    // NOTE: we use 4.3.0.0 as even when you specify 4.3.1.0 you will get a 4.3.0.0 reference as result 
                    // (this will break above when we try to find for every file its reference)
                    //sprintf @"C:\Program Files (x86)\Reference Assemblies\Microsoft\FSharp\.NETFramework\v4.0\4.3.0.0\FSharp.Core.dll"
                else
                    assembly.Location
            if loc = null then None
  