anchor.diff:  { lib
   , stdenv
   , fetchFromGitHub
  +, fetchpatch
   , fetchurl
   , fetchzip
   , cmake
  +, pkg-config
   , gettext
   , SDL2
  +, SDL2_image
   , fmt
   , libpng
   , smpq
   }:
   
   let
  -  # TODO: submit a PR upstream to allow system copies of these libraries
  +  # TODO: submit a PR upstream to allow system copies of these libraries where possible
     asio = fetchurl {
       url = "https://github.com/diasurgical/asio/archive/ebeff99f539da23d27c2e8d4bdbc1ee011968644.tar.gz";
       sha256 = "0vhb4cig40mm0a98i74grpmfkcmby8zxg6vqa38dpryxpgvp5fw8";
  
positive.code:   SDL_audiolib = fetchurl {
      url = "https://github.com/realnc/SDL_audiolib/archive/aa79660eba4467a44f9dcaecf26b0f0a000abfd7.tar.gz";
      sha256 = "0z4rizncp6gqsy72b3709zc9fr915wgcwnlx1fhhy7mrczsly630";
    };
  
    SDL_image = fetchurl {
      url = "https://github.com/libsdl-org/SDL_image/archive/refs/tags/release-2.0.5.tar.gz";
      sha256 = "1zw3k40kbmwc2w9l8fkzrk8maidapmciw3lgcml86pqs9izzddvn";
    };
  
    simpleini = fetchzip {
  
negative.code:     fmt
      libpng
      (SDL2.override { withStatic = true; })
      SDL2_image
    ];
  
    installPhase = ''
  