anchor.diff:      "--user-config=user-config.jam"
       "toolset=gcc-cross"
       "--without-python"
  -  ] ++ optionals (stdenv.cross.libc == "msvcrt") [
  +  ] ++ optionals (hostPlatform.libc == "msvcrt") [
       "target-os=windows"
       "threadapi=win32"
       "binary-format=pe"
  -    "address-model=${if hasPrefix "x86_64-" stdenv.cross.config then "64" else "32"}"
  +    "address-model=${toString hostPlatform.parsed.cpu.bits}"
       "architecture=x86"
     ];
     crossB2Args = concatStringsSep " " (genericB2Flags ++ crossB2Flags);
  
positive.code:     buildPhase = builder crossB2Args;
      installPhase = installer crossB2Args;
      postFixup = fixup;
    } // optionalAttrs (stdenv.cross.libc == "msvcrt") {
      patches = fetchurl {
        url = "https://svn.boost.org/trac/boost/raw-attachment/ticket/7262/"
            + "boost-mingw.patch";
  
negative.code:       find include \( -name '*.hpp' -or -name '*.h' -or -name '*.ipp' \) \
          -exec sed '1i#line 1 "{}"' -i '{}' \;
      )
    '' + optionalString (hostPlatform.libc == "msvcrt") ''
      ${stdenv.cc.prefix}ranlib "$out/lib/"*.a
    '';
  
  in
  