anchor.diff:      mpfr m4 binutils emacs gmp
       libX11 xorgproto libXi
       libXext libXt libXaw libXmu
  -    zlib which texinfo readline strace
  +    zlib which texinfo readline
     ];
   
     configureFlags = [
  
positive.code: { lib, stdenv, fetchgit, mpfr, m4, binutils, emacs, zlib, which
  , texinfo, libX11, xorgproto, libXi, gmp, readline, strace
  , libXext, libXt, libXaw, libXmu } :
  
  assert stdenv ? cc ;
  
negative.code: assert stdenv.cc ? libc ;
  assert stdenv.cc.libc != null ;
  
  stdenv.mkDerivation rec {
    pname = "gcl";
    version = "2.6.13pre124";
  
    src = fetchgit {
      sha256 = "sha256-e4cUQlNSfdz+B3urlZ82pf7fTc6aoloUyDDorAUi5kc=";
      url = "https://git.savannah.gnu.org/r/gcl.git";
      rev = "refs/tags/Version_${builtins.replaceStrings ["."] ["_"] version}";
    };
  
    postPatch = ''
      sed -e 's/<= obj-date/<= (if (= 0 obj-date) 1 obj-date)/' -i lsp/make.lisp
    '';
  
    sourceRoot = "gcl/gcl";
  
    # breaks when compiling in parallel
    enableParallelBuilding = false;
  
    patches = [];
  
  