anchor.diff: -{ config, lib, stdenv, fetchurl, fetchFromGitHub, pkgs, buildPackages
  +{ config, lib, stdenv, fetchurl, fetchpatch, fetchFromGitHub, pkgs, buildPackages
   , callPackage
   , enableThreading ? true, coreutils, makeWrapper
   }:
  
positive.code:       unset src
      '';
  
      # Build a thread-safe Perl with a dynamic libperls.o.  We need the
      # "installstyle" option to ensure that modules are put under
      # $out/lib/perl5 - this is the general default, but because $out
      # contains the string "perl", Configure would select $out/lib.
  
negative.code:       ++ [
          "-Uinstallusrbinperl"
          "-Dinstallstyle=lib/perl5"
        ] ++ lib.optional (!crossCompiling) "-Duseshrplib" ++ [
          "-Dlocincpth=${libcInc}/include"
          "-Dloclibpth=${libcLib}/lib"
        ]
        ++ optionals ((builtins.match ''5\.[0-9]*[13579]\..+'' version) != null) [ "-Dusedevel" "-Uversiononly" ]
        ++ optional stdenv.isSunOS "-Dcc=gcc"
        ++ optional enableThreading "-Dusethreads"
        ++ optional stdenv.hostPlatform.isStatic "--all-static"
        ++ optionals (!crossCompiling) [
          "-Dprefix=${placeholder "out"}"
          "-Dman1dir=${placeholder "out"}/share/man/man1"
  