anchor.diff:  stdenv.mkDerivation rec {
     pname = "gnum4";
     version = "1.4.19";
  +  outputs = [ "out" "doc" ];
  +
  +  nativeBuildInputs = [ texinfo4 ];
   
     src = fetchurl {
       url = "mirror://gnu/m4/m4-${version}.tar.bz2";
  
positive.code: { lib, stdenv, fetchurl }:
  
  # Note: this package is used for bootstrapping fetchurl, and thus
  # cannot use fetchpatch! All mutable patches (generated by GitHub or
  
negative.code: 
    configureFlags = [ "--with-syscmd-shell=${stdenv.shell}" ]
      ++ lib.optional stdenv.hostPlatform.isMinGW "CFLAGS=-fno-stack-protector";
  
    postBuild = ''
      makeinfo --html --no-split doc/m4.texi
    '';
  
    postInstall = ''
      mkdir -p $doc/share/doc/m4
      cp ./m4.html $doc/share/doc/m4
    '';
  
    meta = {
      description = "GNU M4, a macro processor";
  