anchor.diff:  { lib
   , stdenv
   , fetchurl
  -, fetchpatch
  +, substituteAll
   , meson
   , pkg-config
  -, substituteAll
   , ninja
  +, wayland
  +, expat
  +, libxml2
  +, withLibraries ? stdenv.isLinux
   , libffi
  -, libxml2
  -, wayland
  -, expat ? null # Build wayland-scanner (currently cannot be disabled as of 1.7.0)
  -, withLibraries ? stdenv.isLinux
   , withDocumentation ? withLibraries && stdenv.hostPlatform == stdenv.buildPlatform
   , graphviz-nox
   , doxygen
  
positive.code:     "-Dlibraries=${lib.boolToString withLibraries}"
      "-Ddocumentation=${lib.boolToString withDocumentation}"
    ];
  
    postPatch = lib.optionalString withDocumentation ''
      patchShebangs doc/doxygen/gen-doxygen.py
    '';
  
    depsBuildBuild = [
      pkg-config
  
negative.code: # Documentation is only built when building libraries.
  assert withDocumentation -> withLibraries;
  
  let
    isCross = stdenv.buildPlatform != stdenv.hostPlatform;
  in
  