anchor.diff:       stdenv.lib.optional enableStatic "static");
   
     # To avoid library name collisions
  -  finalLayout = if ((enableRelease && enableDebug) ||
  -    (enableSingleThreaded && enableMultiThreaded) ||
  -    (enableShared && enableStatic)) then
  -    "tagged" else "system";
  +  layout = if taggedLayout then "tagged" else "system";
   
     cflags = if (enablePIC && enableExceptions) then
                "cflags=-fPIC -fexceptions cxxflags=-fPIC linkflags=-fPIC"
  
positive.code: , enableStatic ? false
  , enablePIC ? false
  , enableExceptions ? false
  }:
  
  let
  
negative.code:       cat << EOF > user-config.jam
        using gcc : cross : $crossConfig-g++ ;
        EOF
        ./b2 -j$NIX_BUILD_CORES -sEXPAT_INCLUDE=${expat.hostDrv}/include -sEXPAT_LIBPATH=${expat.hostDrv}/lib --layout=${layout} --user-config=user-config.jam toolset=gcc-cross variant=${variant} threading=${threading} link=${link} ${cflags} --without-python install
      '';
    };
  }
  