anchor.diff:        # https://github.com/xattr/xattr/issues/44 and
         # https://github.com/xattr/xattr/issues/55 are solved.
         inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
  -      buildLlvmPackages = buildPackages.llvmPackages_10;
  -      llvmPackages = pkgs.llvmPackages_10;
  +      buildLlvmPackages = buildPackages.llvmPackages_12;
  +      llvmPackages = pkgs.llvmPackages_12;
       };
       ghcHEAD = callPackage ../development/compilers/ghc/head.nix {
         bootPkgs = packages.ghc8107Binary;
  
positive.code:       # https://github.com/xattr/xattr/issues/44 and
        # https://github.com/xattr/xattr/issues/55 are solved.
        inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
        buildLlvmPackages = buildPackages.llvmPackages_9;
        llvmPackages = pkgs.llvmPackages_9;
      };
      ghc901 = callPackage ../development/compilers/ghc/9.0.1.nix {
        bootPkgs =
  
negative.code:       # https://github.com/xattr/xattr/issues/44 and
        # https://github.com/xattr/xattr/issues/55 are solved.
        inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
        buildLlvmPackages = buildPackages.llvmPackages_12;
        llvmPackages = pkgs.llvmPackages_12;
        libffi = pkgs.libffi;
      };
  
  