anchor.diff:  
           cp -d ${gmpxx}/lib/libgmp*.so* $out/lib
           cp -d ${mpfr}/lib/libmpfr*.so* $out/lib
  -        cp -d ${ppl}/lib/libppl*.so* $out/lib
  -        cp -d ${cloogppl}/lib/libcloog*.so* $out/lib
           cp -d ${mpc}/lib/libmpc*.so* $out/lib
           cp -d ${zlib}/lib/libz.so* $out/lib
           cp -d ${libelf}/lib/libelf.so* $out/lib
  
positive.code: 
    test =
  
      stdenv.mkDerivation {
        name = "test";
  
        realBuilder = "${unpack}/bin/bash";
  
        buildCommand = ''
          export PATH=${unpack}/bin
  
negative.code: { system ? builtins.currentSystem }:
  
  with import ../../top-level/all-packages.nix {inherit system;};
  
  