anchor.diff:                        yield "--noframework"
                         yield sprintf "-I:%s" sysDir
                         for ref in defaultReferences do
  -                        if not (hasAssembly ref) then
  -                          yield sprintf "-r:%s" (sysLib ref)
  +                        yield sprintf "-r:%s" (sysLib ref)
                         if fsCoreLib.IsSome then
                           yield sprintf "-r:%s" fsCoreLib.Value
                         yield "--out:" + dllName
  
positive.code:           else 
                sysLib "FSharp.Core"
  
        let getProjectReferences otherFlags libDirs dllFiles = 
            let dllFiles = dllFiles |> Seq.toList
            let hasAssembly asm = dllFiles |> Seq.exists (fun a -> Path.GetFileNameWithoutExtension a = asm)
            let hasFsCoreLib = hasAssembly "FSharp.Core"
            let fsCoreLib =
              if not hasFsCoreLib then Some (fsCore4300())
              else None
            let defaultReferences = [ "mscorlib"; "System"; "System.Core" ]
            let otherFlags = defaultArg otherFlags Seq.empty
            let libDirs = defaultArg libDirs Seq.empty
            let base1 = Path.GetTempFileName()
            let dllName = Path.ChangeExtension(base1, ".dll")
            let xmlName = Path.ChangeExtension(base1, ".xml")
  
negative.code:       let checker = FSharpChecker.Create()
        
        let (++) a b = System.IO.Path.Combine(a,b)
        let (=?) s1 s2 = System.String.Equals(s1, s2, System.StringComparison.InvariantCultureIgnoreCase)
        let sysDir =
          if System.Environment.OSVersion.Platform = System.PlatformID.Win32NT then
            @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0"
  