anchor.diff:        find include \( -name '*.hpp' -or -name '*.h' -or -name '*.ipp' \) \
           -exec sed '1i#line 1 "{}"' -i '{}' \;
       )
  -  '' + optionalString (stdenv.cross.libc or null == "msvcrt") ''
  -    ${stdenv.cross.config}-ranlib "$out/lib/"*.a
  +  '' + optionalString (hostPlatform.libc == "msvcrt") ''
  +    ${stdenv.cc.prefix}ranlib "$out/lib/"*.a
     '';
   
   in
  
positive.code: { stdenv, fetchurl, icu, expat, zlib, bzip2, python, fixDarwinDylibNames, libiconv
  , toolset ? if stdenv.cc.isClang then "clang" else null
  , enableRelease ? true
  , enableDebug ? false
  , enableSingleThreaded ? false
  , enableMultiThreaded ? true
  , enableShared ? !(stdenv.cross.libc or null == "msvcrt") # problems for now
  , enableStatic ? !enableShared
  , enablePIC ? false
  , enableExceptions ? false
  
negative.code:     buildPhase = builder crossB2Args;
      installPhase = installer crossB2Args;
      postFixup = fixup;
    } // optionalAttrs (hostPlatform.libc == "msvcrt") {
      patches = fetchurl {
        url = "https://svn.boost.org/trac/boost/raw-attachment/ticket/7262/"
            + "boost-mingw.patch";
  