anchor.diff:  
   let
     inherit (stdenv) isDarwin isFreeBSD isLinux isAarch32;
  -  inherit (stdenv.lib) optional optionals optionalString enableFeature;
  +  inherit (stdenv.lib) optional optionals optionalString enableFeature filter;
   
     cmpVer = builtins.compareVersions;
     reqMin = requiredVersion: (cmpVer requiredVersion branch != 1);
  
positive.code:       (ifMinVer "0.6" "--enable-pic")
        (enableFeature runtimeCpuDetectBuild "runtime-cpudetect")
        "--enable-hardcoded-tables"
        (if multithreadBuild then (
           if stdenv.isCygwin then
             "--disable-pthreads --enable-w32threads"
           else # Use POSIX threads by default
             "--enable-pthreads --disable-w32threads")
         else
           "--disable-pthreads --disable-w32threads")
        (ifMinVer "0.9" "--disable-os2threads") # We don't support OS/2
        "--enable-network"
        (ifMinVer "2.4" "--enable-pixelutils")
  
negative.code:   setOutputFlags = false; # doesn't accept all and stores configureFlags in libs!
  
    configurePlatforms = [];
    configureFlags = filter (v: v != null) ([
        "--arch=${stdenv.hostPlatform.parsed.cpu.name}"
        "--target_os=${stdenv.hostPlatform.parsed.kernel.name}"
      # License
  