anchor.diff:      sha256 = "03d17mnx6n175aakin313308q14wzvaa9pd0m1yfk6ckhha4qf35";
     };
   
  -  # build phase just runs the unit tests
  -  buildInputs = [ cmake ];
  +
  +  # build phase just runs the unit tests, so skip it if
  +  # we're doing a cross build
  +  nativeBuildInputs = [ cmake ];
  +  buildPhase = if nativeBuild then "make" else "true";
   
     installPhase = ''
       mkdir -p $out/include
  
positive.code: 
    meta = with stdenv.lib; {
      description = "Functions and types that are suggested for use by the C++ Core Guidelines";
      homepage = https://github.com/Microsoft/GSL;
      license = licenses.mit;
      platforms = platforms.all;
      maintainers = with maintainers; [ xwvvvvwx ];
    };
  }
  
negative.code: { stdenv, fetchgit, cmake
  , hostPlatform, buildPlatform
  }:
  
  let
    nativeBuild = hostPlatform == buildPlatform;
  in
  stdenv.mkDerivation rec {
    name = "microsoft_gsl-${version}";
    version = "2017-02-13";
  