anchor.diff:    withToolset = stdenv.lib.optionalString (toolset != null) "--with-toolset=${toolset}";
   
     genericB2Flags = [
  -    "--prefix=$out"
  +    "--prefix=$dev"
       "--libdir=$lib/lib"
       "-j$NIX_BUILD_CORES"
       "--layout=${layout}"
  
positive.code: 
    installPhase = installer nativeB2Args;
  
    outputs = [ "out" "lib" ];
  
    crossAttrs = rec {
      buildInputs = [ expat.crossDrv zlib.crossDrv bzip2.crossDrv ];
  
negative.code: 
    installer = b2Args: ''
      # boostbook is needed by some applications
      mkdir -p $dev/share/boostbook
      cp -a tools/boostbook/{xsl,dtd} $dev/share/boostbook/
  
      # Let boost install everything else
      ./b2 ${b2Args} install
  
      # Create a derivation which encompasses everything, making buildInputs nicer
      mkdir -p $out/nix-support
      echo $dev >> $out/nix-support/propagated-build-inputs
      echo $lib >> $out/nix-support/propagated-build-inputs
    '';
  
    commonConfigureFlags = [
  