anchor.diff:    withToolset = stdenv.lib.optionalString (toolset != null) " --with-toolset=${toolset}";
   in
   
  -stdenv.mkDerivation {
  +let res = stdenv.mkDerivation {
     name = "boost-1.55.0";
   
     meta = {
  
positive.code:       ./b2 -j$NIX_BUILD_CORES -sEXPAT_INCLUDE=${expat.crossDrv}/include -sEXPAT_LIBPATH=${expat.crossDrv}/lib --layout=${layout} --user-config=user-config.jam toolset=gcc-cross variant=${variant} threading=${threading} link=${link} ${cflags} --without-python install
      '';
    };
  }
  
negative.code:   };
  
    enableParallelBuilding = true;
  
    buildInputs =
      [ icu expat zlib bzip2 python ]
  